I dunno.
We have always been able to “get away with” proposing/imposing all kinds of “rules” which our kids could have disobeyed, but didn’t. I see no reason why “Not in my house” need be an idle threat (tho an intelligent parent might phrase it otherwise).
We never tried to pretend that our home was a democracy, or that we were relying upon anything other than our right/power to make and enforce certain rules. We are willing to discuss ANYTHING. But we have no qualms about laying down the law contrary to our kids’ wishes if we deem it appropriate.
Maybe we were able to use our power-of-the-purse to convince the kids that compliance or anything short of outright defiance would be preferable than whatever benefit they might derive from getting their way and shocking/pissing us off.
A lot of it comes down to money. Our kids did not have jobs until they were 16. They get small allowances, we do not pay for chores, and they don’t get huge cash gifts from family. So - in short - they are largely dependent on us for their clothing, toiletries, entertainment, food, etc. So long as they respect our authority to make certain rules (and we try not to abuse that authority) we tend be be very generous, respectful of their wishes, and supportive of their interests. Perhaps they have simply made an economic choice that the benefits they would derive from outrageous behavior would not be worth the costs involved.