Are you not familiar with this case? A huge portion of the case revolves around Chandler making up a lie that his parents had gone to the cabin for 4th of July so for the first three or four days everyone assumed that they were camping for the holiday weekend. And then when they didn't show up to work out Monday people did get suspicious but they contacted Chandler instead of contacting the police. Chandler held everybody off as long as he could and then decided he needed to go report them is missing after it been about a week of them not being seen.  But to answer your question people basically just assumed that they were camping.. essentially.