Well because I bike and many appliances lie idle because: 1. no one is available to repair, 2. repair
costs too much. That is my complaint too with mechanics. Sometimes all that they do is to tighten or loosen a screw or nut. And they charge you so much.
It is a hassle to bring the bike to the bike, and argue and sometimes spit your bile out over a lousy repair
Sometimes the mechanic do not know what to do.
If they sense you do not know, unless the mechanic is close to you or your friend, you are a prey.