Whilst the AI of citizens in Spider-Man isn’t amazing (it isn’t expected to be), you can still interact with them a little bit. Some citizens will either admire you or despise you, depending on your actions in-game and just what their personal opinion is.
Some may come for selfies, whilst some will just shout nice things at you. You won’t get most of these interactions though unless you are down on the ground with them. A few citizens will run up and ask for a selfie, which you can agree to. Or you can choose to do finger-guns at them as you walk past.

Whilst some of these interactions are definitely random, you can force some to happen yourself. Whilst walking down the street, press the Square button on your controller. Spider-Man will greet citizens and mostly just finger-gun towards them.
It seems that the selfie interaction is completely random. In total, it has only happened to me once in game. That doesn’t mean you can’t take your own selfies though. Use the photo mode found in the game menu to do that!
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