I'm sure bars would love to sell to underage people if it was legal, and I'm sure they occasionally turn a blind eye in the name of the profit, but I've literally never once in my entire life heard someone who sells alcohol openly complain about enforcement, or talk about how "unfair" it is that enforcer try to "entrap" them.

Yeah, sure there's far far fewer bar owners than car drivers, but I personally hear drivers complain about speed enforcement like every other day. Avoiding speed enforcement is a massive institutionalised industry, like I said, there's apps, traffic radio, most sat navs show stationary speed cameras. That is not even remotely close to the odd bar owner saying they'd like to sell to younger people. Also, whilst it's absolutely harmful to teenagers to drink alcohol, it at least doesn't directly endanger uninvolved people. The people who are being endangered, the teens, need to actively choose to participate in the illegal activity. Drivers, cyclist or pedestrians following every speed limit and traffic regulation, are still endangered by speeding drivers, and there's nothing they can do personally to avoid that risk. So that's still not an entirely valid comparison.

In my experience, there is literally no other illegal activity that endangers uninvolved third parties which is so widely accepted as normal by the public, that there is literally a major institutionalised industry specifically around enabling people to do that activity without consequences, and I'd be surprised if you can name one.

I'm not talking about just people broadly doing illegal things that endanger others, or even occasionally complaining about them getting caught, my point is just how ridiculously accepted and systemised it is specifically for speed enforcement.