i think it is a self fulfilling prophecy almost though
with the plethora of information freely available on the net, more and more people are doing basic maintenance on their cars themselves. this used to be the bread and butter of your local mechanic
as such, local mechanic has fewer customers, and therefore needs to sting people every now and again to make any money
personally, i'm just starting to learn to do things myself and find it quite handy/enjoyable
others don't have the time/inclincation/tools to do so, and therefore have to pay (sometimes through the nose) for the privilage