I live in the Chicago area where using backing tracks has become the standard for cover bands. Not only for weddings, but also for clubs.
There are quite a few of these cover bands that demand high dollars for weddings and corporate events. I've heard from some former members of one band in particular that gets between 4k and 6k for 3 pc band with 2 vocalists. They generally pack clubs and outdoor festivals with audiences that number in the 2-5K range at the latter. These bands use the defense that they are yhe iones actually playing on the tracks and they are not using them off of original performers tracks.
The sad thing is possibly 95% of their listening audience has no idea they are doing this, and when I point it out to anyone, they don't seem to care.
Now I have had the opportunity to hear a number of musicians from quite a few of these band in an actual live situation, and they are all great players.
Sadly, this has become the norm, what audiences are learning to expect. Not a band performing a song well with the instrumentation they have, but sounding exactly like an original recording, even if a 3 pc band comes off as sounding as big as Tower of Power!!
Personally, I don't think this will change, as more and more younger musicians are using this format to compete with the big money makers out there. This is the future, Karoake with stage performers!