Which pole would this be :D
Not only do some people have more than one child, but public transport comes in many different forms.
On my commuter train, often I can't reach and if I'm in a spot between seats there's nothing else to lean on either! And I'm not that short - 5'3.
I honestly think that most people use common sense don't they - most people can tell whether a situation is a bit iffy or not. On my commuter train, people tend to offer seats to younger children. I think this is good, as it's clear that it's not so safe for them.
I agree with roundabout - I think there are some people who would state that children must stand and then if anything happened say "what was their parent thinking taking them on a crowded train in the first place" etc etc
Fact is it's a busy world and we all have to rub along together, most buses and trains have plenty of people who are not vulnerable to falls etc, and therefore there does not need to be a fight between who gets the seat, the elderly person or the 3yo. Trick is for people to ask young fit people, rather than this business we have with vulnerable groups getting angry with each other.