The problem is, after somebody said you can make £60,000 a year Plumbing everybody wants to get in it. When I was young Plumbers were regarded very much as the bottom of the heap and people thought you were perhaps a bit intellectually challenged if you where one. In other words becoming a Plumber was a poor consolation prize, to be taken up if you could find nothing else to do. In reality it was highly skilled and covered a large range of work from central heating, gas fitting,drainage, roofing and a lot more.
I must admit the work perhaps required more physical skill than it does now in many areas. Being able to bos up a lead corner is not something you can learn fully out of a book, you have to be able to physically do it. I did plenty but was not a natural lead worker by any means or in point very good at it. It seemed some guys could bos them up while reading the paper smoking a ***. It's just that some people appeared gifted like that. Wiping or sweating a lead joint was another area. These in a way I suppose are "arts" or "crafts".
A bit like plastering, the technicality of rendering and skimming may be easy to understand, but doing it to a high standard of finish is not usually so easy. Its a tactile skill.
I often wonder if there would be so many Plumbers today if those old skills where required again? I wonder what they would do if on every job they needed the old "Buzzer" pot and ladle. I suppose there might be plenty of work for the hospitals.
Today Plumbing seems more about technicality than physically dexterity. Don't get me wrong I was probably a better modern type of Plumber than I was the old type. But I worked as one of the old type in my younger years. And I met plenty of Plumbers who could knock me into a cocked hat at it.