The A27 is a major, high speed road and it's not built up. I see your point though, I should have said "The majority of fatal/horrific traffic accidents happen on main roads in out of town areas such as motorways and A roads. However , of course accidents do happen on country lanes and built up...
I don't envy their job but the reality is that this is what firefighters spend the majority of their active service doing. Firefighters will not be called to that many fires in their lifetime, mainly this kind of thing, small fires in gardens and if they happen to be stationed near a motorway...