Well, it certainly seems that this borrowing business can result in a lot of angst. A lot of unfortunate stories here, and in many cases it is a judgement call.
With cheap stuff, who cares, but with a tractor or boat or ATV or truck, it can be a minefield. Probably better not to lend, for several reasons, not the least of which is that it can destroy a relationship!
For me, no one borrows my tractor or truck, and for the atvs or jetskis, only if my daughter is right there with them, and for younger people I go through a testing/training session first. And if they get insulted (no one has), tough beans!
Daughter is coming up with boyfriend in a couple of days. He will be tested. Daughter is nervous as a cat, LOL!