Having fallen off a roof before, I feel like going straight to the 'kill your kids' is a little extreme. I would guess that most falls that result in death are from either a higher than average roof height or onto ground harder than dirt.
Also, how will a child learn about the dangers of heights if they never fall and hurt themselves? You can teach them, and that might work for some, but some children have / need to learn the hard way and that's okay.
My saw stop will stop the blade in <5 milliseconds of contact.
It equates to basically scratching your finger or better (blades move at 3000-3600rpm, so it calculates out to about 1/4 revolution of the blade, max.)
As far as i'm aware, they've literally never had a brake activation failure.
It's pretty much the safest thing in my shop.
Of all the things i'd never let kids play with in the shop, it'd probably be chisels.
Which is ironic, because people think they are a good way to introduce kids to woodworking, when they are probably the sharpest and least safe thing due to how sharp and easy to cause severe injury.
Also, how will a child learn about the dangers of heights if they never fall and hurt themselves? You can teach them, and that might work for some, but some children have / need to learn the hard way and that's okay.