Paging common sense!

On the way home from school one day, Marshall asks me why tractor trailers don't have signs on the back that say "Wide Left Turns." I told him that it was because every vehicle in the US makes wide left turns because we have to cut across two directions of traffic, therefore it is impossible to make a tight left turn. (I don't believe that turning from a one-way to a one-way happens often enough to matter) Don't lorries in the UK have signs on the back that say "Wide Left Turns?"

Either way, I though it was a neat question for a kid to ask, probably not so much if an adult asked. I mean, common sense and all that, right?

Jo asked that out loud the other day while driving down the street.