I'm an auto mechanic and yes, it is unreasonable to expect to borrow tools. Every time you try to give someone a break, that's when your tool walks off. Also, I've found that generally these same people will want you to spend 20 minutes holding their hand walking them through whatever they're doing while you are losing money not doing something you generally get paid for, so that the person can work on their stuff with your tools on your time and usually, your shop space. The sense of entitlement necessary to even make an argument like this is heinous.