In all honesty, what keeps me from interacting with buskers in person is shyness. Even stepping forward to tip someone is a source of discomfort for me. (I should note that if I've stood there for a long time, enjoying the music/art/dance/what-have-you, I will tip quickly because I think that's the decent thing to do.) So I interact more in online venues because they tend not to turn me into a quivering ball of stress.