Sure they do, — unenlightened
I was exaggerating.
The norms changed into a massive clusterfuck. Over the past few years I've talked about it with straight woman friends and acquaintances my age-ish quite a lot. I'd say about 30 people. There were two broad camps.
The first camp believed that being approached by a man (first) in public at all is creepy or predatory in principle - the overwhelming preference for them was not to have it happen at all ever. This was about 25% of the women I talked with. NB, this wasn't framed as a strong personal taste, it was framed as a moral wrong on the approacher's part.
The second camp believed that being approached by a man (first) in public is okay so long as they're not creepy, predatory or intrusive about it. Those situations differed. Some people saw it as creepy, predatory or intrusive if men approached them in public when they were with friends. Some would need friends there for it to be ok. The norms were also very different regarding approach strategies - some people found it creepy/predatory if the guy didn't declare their intent almost immediately (eg trying to make it fully explicit that they're attracted), some people found it creepy if the guy declared his prior to socialising for quite some time. This broad group was 75% of the women I talked with. Broadly speaking they distinguished personal preference from morality, unlike the first group. Some things just gave them the ick which others would require. Such is compatibility.
Both of groups on average would not approach men even if interested (one person I talked with would and has). And both saw the kind of situation you described as a male entitlement to assume it means you can approach them for a conversation at all, never mind an amorous one! Different people have different "clear signals" of their interest, which aren't clarified beforehand.
Of all the guy friends I have, I only know one other bloke who actually talks with women they don't already know (when they have any amorous or sexual intent) in public regularly. The remainder have seen the above and opt out of the clusterfuck, either because they fear the peculiar rejection of being seen as a creep in an unpredictable fashion, or because they don't want to ruin the first camp's day.
People in Camp 1 still engage in the Camp 2 social invitation graces, but they do so as social graces and nothing more.
The overall shift I've seen with these norms over time is the emergence of the first group and those norms getting absorbed by blokes I speak with.
Camp 2 is kind of business as usual for me, what I grew up with, and the norm you're expressing in your post. The default assumption being that if someone meets your eyes, smiles at you, or otherwise engages you in niceties in public that means trying to start talking with that person can be assumed (in principle) to be ok. It's also overwhelmingly what I see when I talk with older people (like 35+) about romantic norms. The Camp 1 people were younger.
It's also very much class coded. Working class dive bars have the camp 2 social norms among the young 'uns. And straight coded - I go to a gay bar and any
bloke who behaves like camp 2 is an absolute prude.
This one is the area that I need to work the most on. I usually avoid women in public places (: It is time to get thrown to the wolves. — Bob Ross
Good luck! Try going out with your friends and approaching women who have other friends there. You get moral support and so do they. Rejection is the default. It always stings a bit but you get used to it.