I know what it is for me.
Most other photography is focused (no pun intended) on the mechanics of technique and managing light to get the shot to record what you see.
Street photography takes that for granted and is intent on telling something, grabbing an idea or a feeling and showing it to someone.
I have friends who love to take pictures of sunflowers and its a big deal when a local farm's flowers are in bloom.
They rush up and shoot hundreds of pictures of flowers.?
And what is there to that?
Someone else in the same spot will get approximately the same thing.
And in the end, there's nothing else. It's a picture of a flower.
With a good street photo you are capturing your own thoughts about life and showing that.
Screw all that technical crap.
Who cares, it's just not important.