Even if the politicians were honest and knew what they were doing.......
...I'll repeat what I've said before - There Is No Money.
Treasury sees £25billion shortfall from income tax receipts amid low wage growth | This is Money
The Treasury is out £108 bn, £32 bn of which is lower Income Tax and NI due to low wages, which is the same size as the entire Defence budget.
..and not one penny of the impact of lower wages on Government receipts was factored into any of the studies that showed that migrant labour is a Good Thing.