...Or even if they see the neighbour's kids have ridden along on the mower and not suffered from it yet.
If you asked a parent if it was safe to do that, I bet most would admit it isn't really. Still, many would do it thinking "I'm more careful" or "I can do it safely". We all take calculated risks everyday, but the consequences of taking this kind of risk are just too horrible to contemplate.
Its really a bit late for these folks (and all we can do is extend sympathy), but its worth it for the rest of us to take the hard lesson to heart.
I have to support Mace here: think ahead and visualize the worst that can happen, then take action (or avoid bad decisions) so the worst can't happen. This is a habit that is worth cultivating for your own safety and to avoid a lifetime of self-recrimination and regret.
BOB