> Physical businesses have liability if they provide age restricted items to children.

Ok, suppose the strip club is the website, and the club's door is the OS.

Would you fine the door's manufacturer for teens getting into the strip club?

Dueling physical analogies is never a productive way to resolve a conversation like this. It just diverts all useful energy into arguing about which analogy is more accurate but it doesn't matter because the people pushing this law don't care about any of them and aren't going to stop even if the entire internet manages to agree about an analogy. This needs to be fought directly.

The OS is not the club's door. The OS is unrelated. The strip club needs to hire someone to work their door and check ID, not point at an unrelated third party. They should have liability to do so as the service provider.