In the Netherlands we have trains with the cab above the passenger compartiment[1][2] but the national rail service has recently revised these and welded shut the passenger walk-through coupling due to maintenance costs and frequent breakdowns of the many moving parts.

[1] photo: https://upload.wikimedia.org/wikipedia/commons/thumb/c/cf/NS...

[2] video of the walk-through coupler: https://www.youtube.com/watch?v=mIi2CDYG7jc