As for kitchen fitters, bathroom fitters, and Odd job men - as there is no consequences for them not following the regs they just carry on regardless
IMHO consequences, and who the customer has their contract is with, have a key impact on how good the workmanship is...
i.e. The majority of "electricians" and/or "person(s) doing the electrics" for the typical; Building extension / Kitchen or Bathroom refurb / Loft conversion / Conservatory - Back-to-a-solid-roof-room alteration / Garden office installation / Garden landscape lighting + water feature pumps etc.. etc.. are just sub-contractors, mates or relatives who know how to join wires, of the builder, gardener, bathroom/kitchen company who the customer has the contract with and who the customer is paying...
They are generally on a fixed price, limited timeframe to get the "electrics" done without delaying the rest of the project...
And as long as they can get something to "work" ok for 6months or more... by the time any dodgy wiring is found..
they are long gone and the customer never had their contact details anyway!!!
So, Not my problem, leave it for the customer to thrash out with the main-contractor..
And the more links you have in the chain.. the more options for "Passing the buck", when the pooh hits the fan!!!!
Whereas electricians working directly for a customer, who has all of their contact details, will generally do the job right first time, as they don't want wasted journey(s) to rectify problem(s) they could have sorted during installation!
Which basically comes back down to, "What are the consequences of how well you do a job if you choose to cut-corners?"