They have buses like this at St Michaels Mount in France. The buses run from the car park to the mount then the driver goes to the other end and it returns without turning round.
If it's a UK bus, the passenger door should be at the left side front by the driver' position. As the door cannot be seen it must be on the other side, and therefore the bus be travelling left to right
Young children have no trouble with this one, they answer straight away (based as said on which country they are in) - it's only adults that start to analyse it.
Just a thought for the AB conspiracy theorists- given that I posted the same problem on here within the last couple of weeks is this further evidence of a link between AB and the Daily Mail?
The puzzle is most often presented without any road or buildings to gauge which side of the road it is on , hence children answer according to where they live.