I was an enthusiast who worked on bikes before I became a shop mechanic.

As an enthusiast, I thought I knew a lot about bikes. Then I became a shop mechanic and found out how much I didn't know. Now I know more, but there's still a lot I don't know. Any time I think I know it all, I go through either a current or older edition of Sutherland's; take some online tech courses with the major component manufacturers; or do something like the Park Tool seminars. Or take something apart I've never encountered before and try to fix it, get it back together. Manufacturers are very helpful with this -- just as soon as I think I have things figured out, they come out with new stuff and standards...

As an enthusiast, I could work on bikes to my own satisfaction. As a shop mechanic, I work on bikes proficiently to any customer's satisfaction. And to the shop's expected margins.

As an enthusiast, if I broke something, I was on the hook to fix it. As a shop mechanic, if I break something, it's on me/the shop, not the customer.

An enthusiast could very well do work to a higher standard than many shop mechanics. But if they are getting paid for the work, they are either vastly undervaluing their time or charging what many might see as exorbitant, shop-like fees.

As an enthusiast, if I work on someone else's bike and it leads to injury on their end, warranted or not, I could be on the hook for that -- my insurance, my assets at risk. As a shop mechanic, there's business insurance and many layers of legal protection between me and the injured party.

So the answer is... it depends on what you mean by better, when you ask if bike repair shops are any better than an enthusiast. Some are, some aren't...