While I agree mostly, you’re acting like getting their hands on an uncontrolled device is hard. Even a decade ago, an old smart phone could be had for a song. Hell, people throw away phones with cracked screens all the time. Then just hop on a neighbors WiFi and bobs your uncle.
Do I think that means all people should have to verify their age? Absolutely not. But this isn’t necessarily something that can be solved with “just be a parent.”