Do they borrow eggs or milk? I had a neighbor once who did that. They never brought them back - not that I would want them to.
The first thing was they needed matches, for a fire. No problem.
A little bit later, they needed a couple of containers in which to carry water back to the camp. No problem (when one camps here, one has to get water from near the house).
When setting up the tent, they needed to borrow a pair of pliers to twist some metal wire. No problem.
Then they wanted to borrow wooden clothes-pins to use in hanging wet clothes. No problem.
That was the first hour they were here.
As it got dark, they wanted to borrow a couple of flashlights. No problem.
They went to town and got beer, and wanted to have a plastic trash bag. No problem.
Just before they hit the sack for the night, they borrowed a shovel, so as to bury things in the morning before they left. No problem.
But man, for people who allegedly camp "a lot," they sure seemed ill-prepared.