Interesting that all seem to think they 'know' why a paid for site is not occupied. And they 'know' it has to be a inconsiderate person.:R
Last year one of the seasonal's spouse died. Yup their site was empty for the whole season. Should she give up her paid site to you because she had a death in her family?
The site next to me in regular paid camping was empty for 4 weeks because the DH had a stroke during their stay and the DW and family were now parked in their RV in the HOSPITAL parking lot to be close to him praying for him to live.
Just saying don't broad stroke it cause you don't know. When it comes to a prepaid site and others calling an RV'er inconsiderate for not occupying it 24 hours is just plain ludicrous and again you do NOT know the circumstances. I could have pulled in the night before and left in the early morning to go sight seeing. And yup I'd be pissed to come back and find anyone's truck in my CG site because some finger pointer thought it was empty and felt it was their 'right' to use it. :R