Have noticed this 'behaviour' more recently lately - I travel on a bus sometimes for work - it gets me in nearer to work than the train station etc.
Have noticed a few times, different parents that some of them happily let their DC swing their legs and kick me... parents rarely say anything or apologise. Last week I glared at the DC as I didn't want them to be the one to be telling them off. One parent did apologise but that was one. This is on different buses. Oh and also feet on seats. I hate and don't put my feet on seats but why is it ok for kids to put their dirty feet on seats?!
I have 2 under 10 myself and if they kicked anyone on purpose or by mistake when out I always apologise and say don't do it again. Also, it's always feet off seats.
Not sure if I'm being a miserable cow or not.