Just a couple examples...
When our new factory was opened 3 years ago'ish, I talked to a tradesman still on site about work...he reckoned you could turn up in London and earn £300 a day, nooo problem. They were crying out for sensible, reliable people, even just to string in Cat5 cables, no experience, no qualifications required. They were already paying people that rate and in his words...they were fookin useless.
A colleague of mine does bathrooms and kitchens privately with his brother. They're flat out, mostly through re commendation. His brother has just gone on the books of a building company, £50k pa plus a fully rigged out van. No stress of being self employed, earning a bit less but far less stress.
I guess when skilled people are short, inevitably rates go up,the higher they go, the less likely someone want little jobbing work, more money to be earned elsewhere.