The OP is assuming or speculating nothing. If you reread his post he is asking a question as to the frequency of "no pays."
Being VERY literal, you, too, are "speculating", assuming that he's referring to "no pays". He's only asking if anyone's witnessed people coming late and leaving early, and whether it's considered rare or common, no more, no less. It's TWO straightforward questions each of which only requires a one word answer: Yes/No or Rare/Common. The INFERENCE is he's wondering if people are leaving with out paying, but it's not the question. However, I do agree that anyone "reading between the lines" can reasonably assume he's wondering if people are camping without paying.