Usually they have volunteers who do maintenance. At my local tool library the tools are well-used, but there's also like 10 of everything so you have lots of backup options.

most places i’ve borrowed things will seek some basic assurances that i know what i’m doing, first.

for example, when i borrowed a MIG welder, the person at the space asked me to weld some scrap metal in front of them before they let me loose with it.