My band play once a month at a small holiday camp. We're a full band, no backing tracks, playing "classic" pop/rock (Beatles, Queen, Lizzy, The Who, Bryan Adams etc.) Some gigs are well attended, some tend to be half empty before we've finished the first set, but as most of the campers have kids we're presuming they're off to tuck them into bed rather than leaving because we could possibly be crap (or too loud). We are only one of two full bands that play here during the summer - the rest of the time they employ the aforementioned duos/trios/soloists with backing tracks. We get paid £200 which gets split 4 ways and we play for 2- 21/2 hours depending on the crowd. The last time we played there, there was a party of people who came up to us at the end of the gig and told us the only reason they booked their holiday for that week was that they knew we were playing as they'd seen us the last time they stayed there.
I think if more holidaymakers gave better feedback regarding the evening entertainment, holiday parks may be more inclined to take a risk and book "real" bands.