Have you considered that the second path you outlined, "giving your body to a master tradesman to get a piece of paper over many years" (in the figurative sense), is in general a necessary prerequisite to avoid the first path of any moron being allowed to "[call] himself a repair man which can and does end in disastrous jobs"?
> I wish I could live in a world somewhere in the middle […]
This world would just be a mixture of both, with many more semi-skilled tradesmen doing many more half-assed jobs, but not having to train as long.
I've done a lot of that type of work myself. It isn't hard to learn how to do it right from books - and I have passed inspection reports to prove it. I've also seen those professionals do a terrible job - to the point inspectors admitted to hurrying my job because they knew the next would be a mess.
I believe you. But not everyone is an autodidact. Most people, for whom becoming an electrician or plumber is the best option among all viable careers, do not have the discipline, aptitude, and intelligence to learn the theoretical and practical knowledge of a trade completely on their own. And vice versa, people who would be able to pull this of, typically have options that are better-paying, higher-status, or less physically demanding.
> I wish I could live in a world somewhere in the middle […]
This world would just be a mixture of both, with many more semi-skilled tradesmen doing many more half-assed jobs, but not having to train as long.