The city streets in basically ever sector are packed to the brim with people in terms of theme and descriptions, but there is a certain limit to the amount of reasonable random player interaction one is going to have when there is 20-70 players available to fill out those virtual spaces. Sindome is actually one of the most consistently populated roleplaying games of its kind, and has been so for quite a while, but text gaming in general is a still a very niche genre and roleplaying intensive games even moreso.
There are many (not always immediately obvious) incentives to get involved with other players, but it will require some effort to go out and engage with players to do so. Bars and clubs and the like are natural gathering places compared to the streets, and you can speak to an NPC bartender to ask them where the party is to help find more players.
I would not expect to be going around and getting in random fights though, except for some archetypes that is more of a MUD type gameplay whereas Sindome tracks more to realism so most characters are not seeing casual daily combat of that sort, although there are exceptions for the players who are interested in that type of thing.
Still there is certainly room to discuss how character progression works and get feedback about it.