> You can't . If you talk to modern city people the way you casually said 'hi' to strangers in the 90s
It is true, in some places, that talking to strangers are generally frowned upon without having a good reason to do so.
The trick is to either only open up the conversation when you have something relevant to say (or funny, seems to work sometimes too), or move to city/country where it's socially accepted.
As someone who used to live in a country where talking with strangers is basically implicitly forbidden and straight up weird, but then moved to a country where it's completely normal, the amount of interesting conversations easily skyrocketed as soon as I landed in my new home country.