I used to work for someone who was better at tiling than plumbing, I used to do some tiling as he taught me but I hate doing it.
Wall tiling isn't one of the subjects taught on the City & Guilds plumbing course.
There is the answer to the shoddy work, Jack of all trades types rather than professional tradesmen.
Plumbers are not plasterers and so on.
Someone I worked for recently had their bathroom tiled by 2 lads, the job was horrible and looked like it had been done in the dark, I asked the customer...