Those bans are leaky, and physical. They aren't censorship, and (almost?) Exclusively ban services or sale of goods to underage people.
They are also costly to implement, and require a lot of state effort to enforce.
These digital checks, if done "right". Are cheap to implement, and hard to get around. They don't easily let adults allow a kid to do it anyway. And a government can trivially check if a whole swath of businesses is implementating it.
That last point makes it very easy for governments to use this for widespread ideological interventions. With very little option for others to push back, because few people are involved in enforcement.
These digital checks, if done "right". Are cheap to implement, and hard to get around. They don't easily let adults allow a kid to do it anyway. And a government can trivially check if a whole swath of businesses is implementating it.
That last point makes it very easy for governments to use this for widespread ideological interventions. With very little option for others to push back, because few people are involved in enforcement.