Originally Posted by
himespau
Never said it was a smart decision, but an amateur lawyer who got all his training reading internet forums might think putting a sign out like that might cover the co-op's ass if someone put something on wrong and got hurt (when in fact selling the parts and not letting them install it there would probably be safer from a legal point of view).
I think if the customer does the work, no matter where, the customer takes all the liability. No one can ensure that the customer knows anything, or uses whatever s/he does know. If it is a professional (or even a volunteer) working under the auspices of the establishment, the establishment is responsible until the tires hit the sidewalk.