I've spent a fair amount of time trying to explain to people that just because you're legally right doesn't mean that you want to spend years of your life (and a small fortune) proving it. Yeah, I can be a dick to a cop, and yeah, I'll eventually be cleared, but it's honestly just not worth the hassle of getting beaten up, getting tased, spending a couple of weeks in jail, and then fighting the charges and the subsequent appeals to prove that I'm right. Hell, you can't even sue them anymore for violating your civil rights since they're immune in just about anything they do. When it's just a basic traffic stop you're best off playing nice. If it moves beyond a basic traffic stop, then maybe you're better off asserting yourself.
"Am I being detained" isn't going to get you anywhere. It's a very legitimate question with very legitimate legal implications, but Johnny has years of experience getting around it. What's your answer going to be when he says "no, but you're not free to go, either?"
What is helpful is knowing what he's actually doing. If he pulls you over for a moving violation, then says he says he's going to let you go with a warning, or a trivial "failure to obey a sign" kind of thing, mission accomplished. Being nice paid off. If he follows up his act of generosity by asking if there are any drugs in the car, the nature of the stop is not what you thought it was and that courtesy may well work against you. That's when it may be time to start asserting yourself. A cop who pulled you over for speeding is not the same as a cop who pulled you over to snoop around and see if you're worth fucking with, and they shouldn't be treated the same.
Their original point involved people being in a dispensary that had been raided, though. When the federales get involved things are sufficiently bad enough bad that pissing them off isn't really going to land you any deeper, and respectfully asserting your right to shut the fuck up is obligatory. The DEA is
not going to let you off with a warning because you were being civil, and they
will use anything you say against you.