It's starting to change in places, including in the US.
The reality is it's not the smartphone, but the slot machine type software running on it.
There's more than enough science that placing this kind of content in front of humans before their prefrontal cortex is fully formed at age 25-26 leads them to leaning on the pre-frontal context of the adults around them, and missing that, whatever they're spending the most time with that's then possibly raising them.
Screens at lower resolutions and quality didn't seem to be as much of an issue compared to the hyper saturated motion with sound effects that are consciously chosen to keep eyeballs.
Like anything, digital can be used for good, or bad, and in lieu of good, the other can to happen and become more of a default.
I agree but it is much harder to stop people from building slot machines than to stop children from using them. Even easier than telling people to stop using them.
And hey, maybe if we actually take some autonomy and remove that market from actors who don't want to build the things the market is requesting then they'll actually build the things the market is requesting... it's easy to say we want something but no one listens when we still buy the thing we say we hate. Maybe it's addiction but it's still hard to fight against. (Though we could still do better by accommodating those who are trying to break the network effects. You can complain how hard it is to get off Facebook but if you're not going to make the minuscule extra effort to accommodate those who do leave then how can you expect the ground to be laid for you to?)
At the end of the day though, with kids, the OP's argument fails because it either assumes smartphones are an inevitability or that the benefits outweigh the costs. It's a bad argument.