So the question is how many people are at the show because they found the band on Spotify/Pandora/Youtube/etc? My guess is it's a pretty significant chunk. It's the best marketing tool independent artists have ever had, especially compared to the days when you had to buy/borrow a physical CD just to check out their music.

Musician here.

For most local bands, nobody discovers you on Spotify. People find out about your band because you shared a show with another band they like.

After you are discovered by the new fan, they may later search for you on Spotify. But Bandcamp is more likely.

That assumes they even remember who you are. You have to play multiple shows in some areas, make a big impact on the audience, maybe have your stuff played on the local college station and then, just maybe, people will give a shit about you.

Lots of good music on bandcamp with less than 30 plays, and that's why.

Fair enough. I think it's mostly an advantage where you're big enough to tour but not big enough to consistently sell out your shows.

In my experience, people go to shows with local bands because they're either an opening act for a bigger more well-known band (as ssaew333 mentioned), or because they've already seen them before at a festival, or because of recommendations from their friends. Word of mouth is huge when it comes to smaller bands.

What streaming does is that it makes it so much easier to check out a band when a friend says "hey, give this band a listen, they're pretty good!". The initial recommendation comes from a friend, usually not the streaming service.