I understand your thinking. However, if you are a family of two adults and three children, and you buy a 4 seater, you're an idiot.
I understand the idea of being caught short, and needing to make do. But even that still doesn't fly with me. You make other arrangements, it really riles me people not caring for children, even if thats 'just nipping 'round the corner' with an extra child in the car. It really doesn't take much, one careless driver and that child's gone. Forever. An it's completely avoidable in 99.9% of circumstances.
Everyone is entitled to their own opinions, of course, but those that believe contrary are certainly wrong in this case.