As a former bar and club owner, I can share my experiences, from European perspective. Went often, for years to places like Perugia, Italy ,
http://www.umbriajazz.com , or to capitols like Berlin, London and many more. To The States as well, but I guess the Frogman can say more,he is at home there.On all these places I tryed not only to go to clubs, but also to speak with owners or menagers to understand better how the 'scene' looks from their perspective. I do not like to make general conclusions, because the attitude toward music is specific from town to town, or even from place to place,(the biggest and probbably the best jazz festival in europe is in Switzerland
http://www.montreuxjazz.com ) but I think its pretty obvious that jazz music (as far for the number of people interested for it) is a very 'endangered species', for decades now. Reading just recently here, a post from a man from San Francisco (sorry, forgot his nick now), where he says that unless you do not have Diana Krall in a club, you cant hope for a bigger audience, says it all. The market has no mercy. In some places,in Europe, the jazz clubs and events are sponsored by the town or by the state, as a projects of culture. As for the prices, if someone is interested,I can say only that local 'stars'(that play music which could be used for torture chambers in Guantanamo) in my country charge for a one night gig in a club, between 6t usd up to 35t usd. House music 'D.J.' depending of their popularity would ask for even much, much more. Last couple of years we have a house festival in my home town
https://youtu.be/qKH9DpPNCrM, with 'music', that needs no comment, but that has brought more touristic attention than all combined efforts of a whole country. Again, they are also sponsored from local and state officials. Would they do the same if it was jazz? Hardly, unless it could bring the crowd.So, to cut long story short, there is no culture without welthy sponsors and I guess the same is in the US, been to famous NYC jazz clubs that were half full on Friday night, despite the great artists playing there