Here in Queensland where I live in Australia we've the same thing with e-bikes and kids, the showing off without a helmet, injuries & death etc,
We've new laws that aim to reduce the carnage (ask any hospital emergency department professional) and limit e-bike and e-scooter speed to 25 km/hr (divide by 1.6 for mph) or 12 km/h on footpaths.
This one may be of interest :-
"E-scooter, e-skateboard and e-unicycle riders must be aged 16 years or older to ride unsupervised. Children aged 12-15 can ride only under adult supervision.
Parents will be fined for under 16s riding illegally."
No one expects that there will be 100% adherence but it makes a line in the sand & I've not heard any negatives now it's in place.