Regardless of what direction a player faces initially, boarding a minecart forces their head to face south. This is an issue on all devices tested so far, on Bedrock edition and has been an issue since 1.14.
Here is a video demonstrating this bug in action - https://www.youtube.com/watch?v=eCNHmJoHNs8
This bug also affects rideable mobs, but does not affect boats.
Thank you for your report!
We're actually already tracking this issue in MCPE-55277, so I've asked for this issue to be resolved and linked as a duplicate.
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.
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