I agree with Don Mason here completely. The corporations are required to provide an entertainment budget for the places and expect to pay for events of all kinds. Those folks who think they are doing a good deed by playing free are not really doing what they think. And often they are rank amateurs who couldn't get a real paying job.
It certainly depends on where you live...laws are different from province to province in Canada, as well as varying from state to state in USA...also a big difference in privately run and government controlled homes.
The people in my area that perform for charity are all well known professionals...it's basically a "gentleman's agreement" that no one charges, and it is only for certain homes and under certain conditions. On some occasions there will be several acts performing, much like a mini-concert.
One thing for certain, I got lots of non NH work because of the exposure, as have many others...an hour freebie once in a while is simply considered good business and healthy community public relations.
In any case, no one is taking from anyone else.
Ian