It would seem the chief argument you rely on is your sense of moral outrage. That’s the ploy when there is no logical argument to substantiate your posture. Sorry, but 16 is more than old enough to know what he or she is doing. If they know what they’re doing with a peer or even someone slightly younger, don’t expect me or anyone else to buy the idea they turn into helpless innocent little babies just because the older partner is over the age of majority.
Teens that age and younger can and do plan in devious ways to get fake IDs to buy tobacco and alcohol and to get into establishments (adult clubs) where minors are barred and they lie about their age without shame or remorse…until they get caught and held accountable. They lie about their age to have sex with an older adult. Does the teen ever pay for their complicity? NO!! Only the adult gets blamed. I say culpability is 50/50.
I personally think any teen who lies about his or her age in order to have sex with an adult should be charged with as a sexually delinquent juvenile and be treated accordingly. They KNOW what they’re doing.