Banning garage sales may be part of the community charter the same as not being able to park a truck used for work in the driveway. Stupid if you as me but people agree to these rules to live there.
As for allowing only one a year, well, someone realized that some people use 'yard' or 'garage' sale as a way to have a small home retail business without paying sales tax. (OH MY!!) can't have that now can we. I agree that it interferes with free enterprise.