[bombcar]

The way this usually works in the USA is a “homeowner’s exemption” - you can run cat6 in your house all you want but you can’t charge others to do it for them without certification/licensing.

Which can lead to all sorts of fun homeowner specials when you buy an older property.

[Hizonner]

You can also have fun times if they used "professionals". Electricians, and especially plumbers, are like termites. In the course of following their own imperatives, they often do serious damage to the building structure. Sometimes they also screw up their own trades, but more often they screw up something else.

[bombcar]

Yeah, even if you're having a custom home built, you either need a really diligent prime contractor, or you need to visit it every day, because nobody cares about anyone else on the job site, and very few companies have all the trades in-house.

Definitely have an independent home inspector do an inspection before the sheetrock goes up. Issues are cheap or free to fix before that step.

[ColFrancis]

A genuine question, from someone who doesn't have the option: would you prefer to have it banned?

[bombcar]

No. It’s very nice, but for things like actual electrical and gas work, a permit is required.

Many people don’t pull permits however - it’s something to be aware of when buying older homes. The advent of arc breakers and GFCI have reduced the chance of serious harm in these areas.

And I’ve also seen (and done) work that was significantly above the base line contractor level (that nobody would pay for usually) just because it was the homeowner bothering to do things very right.