Yeah, this is something that changed from Concorde times (and possibly even sped up its very demise): the market for reliable, high-quality private planes has grown massively. It's now pretty easy to shuttle between the big cities in almost complete privacy through secluded airports.

> You get treated like a criminal for forgetting your shampoo bottle is 2 ounces too big for some dipshit TSA agent's liking,

Enforcement is super uneven, and etc, but IME, they just open your bag, find the thing, and then offer you the choice of tossing it or going back to check your bag. Depending on how much you paid for your shampoo and how much a checked bag would cost you and if you have time to do all that and then wait in line again, I expect most people toss it.