I've played in pub bands and part-owned a pub at one stage so I have some sympathy for both camps. On the one hand margins have gone so tight that to pay a band £300-400 on top of staff and overheads etc really puts a dent into a nights takings, especially if that band hasn't generated that revenue in extra customers. Plus there's the lost floor space, hassle with neighbors, police , etc and now insurance ("I tripped over that guitar cable, honestly guv"). Its no wonder they dont bother with it or just get a man with a guitar and a beep box.
On the flip side there are unscrupulous landlords that will pay you a pittance while you pack their pub with thirsty revelers, I've experienced this on a good few occasions where the pub would be jointed and we come away with €150 between 5 musicians. I think a pro-rata payment would be the fairest in an ideal world.
I found that the only way to make serious money gigging is to sell your soul and do corporate events, weddings etc. Life is too short and there inst enough shower gel in all the world that could wash away the shame of being reduced to playing 'rock the boat' to a bunch of idiots with ties around their heads.