Not trying to bash you here. But I was honestly wondering if there were any upsides to leaving Europe. With this you’re practically adding to that there’s none.
What if no one wants to do those jobs who's from the UK?
While Brexit is surely a major factor here, obviously we also have the pandemic that has a particularly severe effect on some of the same industries. There are other significant factors in specific industries, such as the terrible conditions for lorry drivers in the UK compared to elsewhere in Europe. There's also the bizarre own goal of the government pushing ahead with its IR35 agenda at a time like this, which again hits some of the same industries particularly hard.
It's going to be difficult to discuss these industries rationally and consider potential changes that could be made without some reasonably objective way to evaluate all of the relevant factors and how much they are contributing to the current situation in any given industry. As with almost anything to do with Brexit or the pandemic, it seems unlikely there are any simple and universally "right" answers.
The issue with the EU free movement was lots of eastern European labourers undercutting UK salaries and driving up rental prices by living 6+ to a house, etc.
I find it ironic that Americans criticise Brexit when they themselves benefit massively from the extreme restrictions on immigration (compare Tech salaries in the US and Europe for example!).
I voted Remain but can see some benefits in helping to improve wages and strengthen trade unions by limiting the availability of mass unskilled labour which harms the economy (aside from business owners), see https://theconversation.com/the-return-of-the-hand-car-wash-... for example.