From a safety viewpoint being seated on public transport is probably a lot safer.
As for giving up seats, in the UK we have seats that are priority for elderly, disabled, these are usually near the front of the seating area, If a child is in a buggy / stroller then their parent can use that area. But if a wheelchair gets on then they can use that area, buggy / stroller must be folded.
I am not sure what happens if a disabled child is in a buggy / stroller, I would hope common sense would kick in in that rare situation.