I've only come upon ONE foot controller that was grounded...I don't know, maybe he was trying to ground the thing but the wiring was such a mess above the foot that there was a better chance of getting shocked by the taped up mess of wires than the foot controller.
I have a 3 year old grandson who is here almost every day. I try to keep scissors up and machines off but don't worry too heavily. He is warned meemaw has lots of sewin' machines and they have sharp stuff that could hurt you, so don't touch ok? He's ok with that. I don't have fears he will electrocute himself. There are plenty of other ways to get hurt around here if he were to put his mind to it. Kids can always get into something if they are so inclined.