Age verification sites were never required. This is a new artificially created business model. There is no need for age verification on the server side. Parents of small children can handle it assuming minor changes or reverts to devices and some apps to look for the RTA header. The server or CDN need only let the client know it may contain adult and / or user generated content via one simple header. [1]

Not perfect, nothing ever is nor ever will be. Also never try to block teens, that is a foolish losing battle.

[1] - https://www.rtalabel.org/index.php?content=howtofaq#single