Pretty much all of those things (except bleeding breaks, but again just dont buy a stupid bike) are very easy to do. Fact of the matter is a bike mechanic is just never going to have enough expertise that they can command higher pay when the average person is just going to do the repair themselves if you charge more. Car mechanics aren't particularly well paid for that matter, and a car is an order of magnitude more complicated than a bike. You can take most of a car apart with a one ratchet set. The tools you need to do anything on a bike won't exceed a 100 dollars unless you go and buy all park tool stuff. The average person doesn't ride their bike enough for it to even need maintenance more than once a year. Basically that leaves bike mechanics with a customer base of enthusiasts with more money than time on their hands, at least in regards to where most of their work would come from. Used to like to watch this bike mechanic on youtube, I think he ended up selling his shop because fixing old bikes to sell them wasn't making enough money.