Parents can just do this. It's far more expensive to not do it.

When all the kids in school have a smart phone it’s extremely hard to be the one kid and parents that don’t.

So, so much easier and more effective if they’re just banned for all kids.

prohibit all proprietary software

That won't help. They'll open-source it, and the addiction stays.

Haven't you heard about the four freedoms? The software which meets this criteria is totally safe.

Define a smartphone.