Wrong answer? Right Answer?

I read CoffeeRings' latest post and it reminded me of something similar that happened to my son in school.

My son, who's in 2nd standard, was doing his homework, answering questions in a chapter titled "Safety". It talked about safety at home, in school, at play and in the outside world.

One of the exercises was to tell whether a statement was true or false. One of the statements was, "It is okay to walk on the road."  which my son, based on his experience, marked True. He was surprised when his teacher marked it wrong. I had a hard time explaining the difference between the 'expected answer' and the 'actual answer'. (This is the same kid who refused to walk on the streets in the early days after we'd returned from abroad, saying that streets were for cars.)
Another time, there was a question about how different rooms/areas in a home are utilised. My son wrote that he did his homework on the dining table (which is true, he does). His teacher marked it wrong saying that the 'right' answer was 'study table'.

While I do agree that the teachers have to set some form of uniformity in grading answers, I wonder if we are not confusing the children this way or if we are teaching them to lie just to be 'right'.