We're about to cross into the territory covered exhaustively by threads about that "Open Letter to a Bar Owner." I'm not the thread police, so if that happens it happens - although it's a slightly different topic.I think you've missed the point here, is turn about not fair play? if not, we might as well stop playing in clubs altogether, would you go to your day job and not get paid for your labor? I hardly think so.
I do think that here we get into the shades of gray about the kind of place you're playing. If it's a bar, where people go to drink, and there might be a band playing Mustang Sally for their entertainment, that drives behavior one way. If, on the other hand, it's a live music venue where the main objective of the people who are there is to see the band advertised as playing that night - and maybe they will buy a drink or two while there - that is something different. As a band, you kind of have to understand which situation you are in, and how that changes your job.
I just simply think that there are a lot fewer places in general that feature or have live music now than 25 years ago, and live music is used even less in non-bar situations like weddings and parties. All of which lead to substantially lower gig opportunity.
