Please note, this is something of a duplicate of https://bugs.mojang.com/browse/MCPE-60245, but the response there is incomplete, and not applicable.
As described in the linked ticket, a minecart with hopper will pull from another minecart with hopper if it is one level up and to one side, but only in the Bedrock versions of Minecraft. The Java edition of Minecraft does not exhibit this behavior. There is no expectation for this behavior to be the standard; it is illogical, and does NOT match the existing behavior in the rest of the Minecraft codebase. If this were truly "working as intended", it would be this way in both places.
The statement of the minecart with hopper pulling in items from a slightly wider range than the cart itself does NOT explain this behavior for two reasons:
It is not collecting loose items; it is pulling from another container at a MUCH farther range than it should.
The size of the minecart is smaller than a block, so your calculations appear to be starting at the wrong place, and are basing it from the outside of the block the minecart is sitting in, and NOT from the width of the minecart itself.
This is not a matter of a feature request; this is getting the behavior corrected to do both what is described in the Wiki (which it does not right now), as well as match the other half of the Minecraft codebase.
Linked issues
Comments


To add to the reporter's mention of the illogic of this behavior, it only occurs if the upper hopper minecart is to the south or east of the lower one.

Thank you for your report!
However, this issue is a Duplicate of MCPE-57637.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
If you haven't already, you might like to make use of the search feature to see if the issue has already been mentioned.
Quick Links:
📓 Issue Guidelines – 💬 Community Support – 📧 Customer Support – 📖 Game Wiki

Anybody that has used the "Search feature" of JIRA (and I use that phrase extremely generously) is very familiar with the fact that it is, in a word, useless. I did perform a search, and that is how I found the closed ticket I referenced in the original body of this report. The one you linked to did not get returned via search, so your implication that I had not done that step is both ill advised, and inappropriate, as it would be obvious to the most casual of observation that the only way I would have mentioned another ticket here is if I had searched for and found it.
So while I appreciate what you think you're trying to do here, you have also been super trigger happy with that "This is a dupe" button, and while yes, this one is indeed the same issue as the other one, you do not appear to be doing the proper due diligence with these reports. Given that this is literally the only way for Minecraft players to get any level of technical support from the developer, seeing this type of behavior, especially if it had been someone's first experience with the system, is extremely offputting, and does not help improve the quality of issues being reported. You'd merely see less of them as people just throw their hands in the air feeling that it is pointless to even bother in the first place.
And, yes, I understand that the Helpers are unpaid volunteers and not employees of Mojang, but the fact of the matter is that when people see the bolded name, it carries with it an additional layer of responsibility. I say this not to be rude or condescending, but as an opportunity for improvement moving forward. As I said, this is the players' only lifeline into Mojang, and it's tenuous enough already. Thank you, and good luck.

Erin,
By using the Mojang standard, formal duplicate comment, I was not intending to imply that you hadn't made a search. In fact, I am grateful that you mentioned another report and took the time to test this bug and write a careful description. Sometimes we do resolve reports forward if a newer ticket is more clear or has more votes/watchers, but generally we try to resolve backwards to the oldest report. In this case, I found the older report first and confirmed it before finding yours. (Helpers have the ability to mark reports "confirmed" based on their own testing, or "community consensus" based on finding multiple reports or comments describing the same issue. This is a crucial step in getting the report to be worked on by the developers.)
I admit I might have made a mistake in how I read your character creator bug report. That was a few weeks before I was recruited to be a Helper on this site, and I was mainly trying to get attention to an issue that was bothering me, too. I chose not to respond to you on that because I saw no reason to challenge your clarification and at the end of the day, my comment on the ticket is just one opinion. It's up to the developers to sort out how to fix things. But now that I am on the Helper team, I am trying to more careful in my statements, for the reasons you mention, and because of the responsibility involved in confirming reports.
I know getting a formal, standard response on an issue can be off-putting. Please don't take it as a sign that your insights are not valued. In the long run having standard responses that we use as a best practice gives the volunteer moderators and helpers more consistency, objectivity, and focus in our communications. It is not meant to be dismissive. I hope you will continue to bring your insights to the issue on this bug tracker.
Lastly, I want to make clear that the bug tracker is not meant to provide technical support. Moderators and helpers do often provide technical clarification and workarounds as a courtesy, but the purpose of the comment section is to provide additional information on the bugs themselves. This policy is enforced very loosely, but it does guide the helpers' and moderators' styles of engagement. Along those lines, tagging a report as a duplicate is not like calling it "redundant" or "unoriginal," it rather serves to help quantify how significant the problem is in terms of how many players are hurt by it.
Bottom line, I appreciate your contributions and feedback. I hope we can work together again on another issue.
Tim
Some additional support for this - this behavior does not happen with hoppers that are above and to one side of a minecart with hopper which has a hit box of a full block, so if the minecart with hopper were really pulling from that much of a range, it would pull from a hopper in the same position. This does not happen with any of the full block sized containers in the upper position:
Dropper
Dispenser
Furnace
Blast Furnace
Smoker
Barrel
This is something unique about minecart with hoppers interacting with each other, NOT general minecart with hopper behavior.