Yes, the analogy is the burglar getting into the house by asking you to open your door for them. Adults are permitted to decide such a thing, because they know the risks and are expected to be able to reason about that. When an adult has decided, then there is no problem, as far as age verification is concerned. We have regulations when adults are in fact not able to decide such a thing "correctly".

We already have penalties for adults mistreating children by exposing them to dangerous things, but this is orthogonal to age verification.