I work part time at a Wal-Mart, and I can tell you that this observation is absolutely true. The store I'm in is crawling with them- not that there's anything wrong with that [/obligatory Seinfeld reference]. I would also note that there are several elderly people working at the store, as well a few handicapped people, so this store apparently hasn't received the memo yet.
After I retired in '99 I worked in security at Wal-Mart for about 6 months until I decided that I just didn't want to punch a clock anymore.
I was standing near a young checker one night and she called me over to her register. She pointed out to me two men, about my age (I was 54 at the time) standing in her line and they were kissing. She wanted me to make them stop because it was disgusting. I told her that as far as I knew they aren't breaking any laws and there's nothing I can do about it.
That was her last night at work at Wal-Mart.
Nothing to do with this story but the funniest thing I experienced on that job was the night I caught three 13 year old girls shop lifting Early Home Pregnancy testing kits. They begged me not to call their parents, so of course that's exactly what I did. They had some 'splanin to do!