The bug
Prior to 1.6, one could break a minecart or boat while inside it as a simple, easy, functional way of collecting the minecart and exiting the track.
To reproduce
1. Get in minecart.
2a. Place torch on block that minecart is on (only when off-rails).
2b. Break blocks through minecart bottom (including rails).
Linked issues
is duplicated by
Comments
I don't think it's intended because breaking the minecart in 13w26a resulted in MC-18969 yesterday but in 1.6 you just break the block under the minecart.

Maybe caused by the fix of MC-12241
Actually it was MC-14355. You would always hit the horse cause of it`s large hitbox.
Confirmed.

This sounds like an improvement to me. Now you can interact with the world without accidentally hitting your mount.

@Torabi: Yes, but you cannot even hit it deliberately...
In some situations it was quite handy to kill the minecart, e.g. when your train station is switched to run-through but you want to halt. Of course you can dismount by lshift, but you have to let go the minecart.
i guess this accurately covers the issue that i have been having... i cant even play my game because of this glitch/bug. Mine occurs for the windows 7 though so I'm not sure...
apparently you now have to use the dismount button (currently c) to exit a minecart. A warning would have been nice =P

Is this still a concern in the current Minecraft version? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.
Indeed it is
This just happend to me, whlie riding a boat, I think. I also experienced, that I wasn't able to move the boat siedways using a/d. Maybe that is also connected to this bug.

@Achim Sinn: That's MC-14521
Voted. I'm rather worried about the second part of the title, not being able to destroy a minecart while riding it. If the player doesn't have the option to break a moving minecart while riding it, then most probably it won't possible to break it after having dismounted.
@Marios: Nope, you can break a boat or minecart when you're not in it (I tested it in both Creative and Survival).
By the way, when breaking it in Survival, you have to punch it a few times to destroy it instead of holding down left click, like killing a mob (probably because it's an entity; was it like that before 1.6?).
@ BoxFigs: The problem is that you cannot break a minecart while you are in it as said already. I know that it required quite a few hits to be destroyed in 1.5.2 but in 1.6.2 you can't even hit it because it acts as if it is a ghost.
You guys know its because of the minecart controls change to match horses. Baisically when you ride a horse it goes from Mob to "Vehicle" and since the Minecart is already a "Vehicles" when the made it so you couldn't hit your horse when riding on it, the function became true for the other "vehicles." They made it so you couldn't accidently kill your horse when riding it and thus this happend with the minecart
Yes, I know that by now. Still I had to add Stoppers to my trainstations to prevent minecart going on, after I left them and I had to redesign my Harbor area because it was to narrow to navigate with the new boat controls and it was part of the desing to just break the boat in order to leave, which doesn't work as well.
This has made my entire rail network useless and is a pain in the ass. If I want to get out of a minecart mid track, I have to exit it, and then RUN LIKE HELL to try and catch it before it hits the next set of boosters. Why couldn't I just shift click to break it or something? Or click to break it, shift click to place things through the cart? It's the most annoying thing in the world and has made rails completely useless to me
and I LOVED rails 😞
Still an annoying issue in 1.7.4. Please fix this. It's a mechanic-breaking issue that cripples minecarts and rails
I cant use minecart at all :/ please fix!!!
This is a major problem, Is there a quick fix though? I have no way to get out of my minecart. I'm stuck in the middle of perfecting my space. Lol

Press LSHIFT
Correct me if I'm wrong but ithink this is supposed to happen (new feature in 1.6) :-/ because so you can shoot throug it with a bow! also you can leave it with "crouch"

Confirmed for 1.8, though may be intended.
Confirmed for 1.13.1.
Affects 1.16 Release Candidate 1
Relates to MC-270247

Relates to MCPE-180035, MC-278589, MC-278295 and MC-69881.
I believe this is intended in regards to MC-13772.