Also, literally who cares. This isn't politics. Zoomers and millenials are very left-wing and that hasn't changer significantly in recent years. This isn't happening at scales that are shifting the political landscape. Idk why there is an obsession with this shit.
The coffee shop/library thing is questionable, and avoid flirting with your waitress or bartender unless you're someone they know or are in the same local service community and have some connection there. You can socialize at the same spots, but flirting on shift can be a bit aggressive and you're gonna get weird signals because their job is to be the smiling face so they can't tell you to fuck off and they also can't leave because they need to.
If you do want to do want to "make a move" in a situation like that, always open with smalltalk, give a compliment, and move on. If you hover, stare, or push then it becomes a problem.
If you're taking about patrons in these places that's different, they can leave and aren't bound by their employment contract to be nice. So you can lead with smalltalk, and just go from there.
Also smalltalk and compliments aren't code for discussing appearance, a compliment could just be "nailing it with the matching bag and shoes" as opposed to "your very beautiful" and smalltalk should be situational at first with stuff like "maybe one day we'll be out of this line" or "have you ever read Das Capital Volume 1 by Karl Marx?" you know, keep it light and inoffensive.