I know a few people that used to work on sites that had to leave because they weren't willing to travel up to London and work on sites from 8 till 6 for £80 a day. Funnily enough, two of them have recently gone back as the wages have got better since Brexit.
Let's get something straight, here. I work the area between Liverpool and Leeds, mainly around Manchester these days,and our labourers earn more than £80 a day, whilst site-based tradesmen haven't been on £10 an hour since the depths of the recession, back in 2008 to 2010. So either you are spouting b0llox, or your mates are.
A mate of mine delivers and repairs concrete pumps to sites and he can only talk to the foreman because not one of the workers can (or maybe won't) speak English. How on earth do they get theit CSCS cards?
Well, in point of fact it's supposed to be the foreman your mate is talking to in any case (it's called "chain of command" in the military). But never mind.
The reality is that your great hero, Margaret Thatcher, shut down a lot of technical colleges and night schools and decimated the apprentice system (NVQs do not replace C&Gs), and Tony Blair then finished off the job by persuading young people that they all needed to have degrees not C&Gs. On top of all this the current shower of sh1te have done sweet FA since 2010 to improve technical education in the UK despite voices in the industry calling repeatedly for it
Any way, the result is that we have had, for more than two decades, a severe shortage of young people willing to come into an industry which is often perceived (and often described by middle class teachers as) dirty, dangerous and (sometimes) under paid. This is in no small part responsible the decreasing quality of apprentices we've had over the last 20 or so years, many having poor literary and numeracy skills. Given that this situation was self-inflicted by the HMG UK and occurred before the arrival of workers from the east European accession states in about 2001 to 2003, you can hardly blame employers for wanting to plug major gaps in the skilled workforce. In other words it wasn't down to the EU - it was our own politicians who created this situation.