I can't imagine any ordinary "Joe Shmuck" parking there like that. I bet they were part of a group, an entertainment group, a group of musicians, or actors doing a performance and were parked there while their performance was going on. Notice the vendor both with the canopy on the left of the photo. Probably a street side booth to sell their memorabilia.
Went to a Kenny Rogers concert a couple years ago. Same situation... except the RV's (2 of them) were in the parking lot at the College auditorium where they were performing. And their booth with memorabilia was right inside the door of the auditorium.