2. No employer will employ illegally and deduct tax & NI. The fine is very high.
And yet.
3. Refugees do indeed work illegally while paperwork is being sorted out, but that sort of work is low-paid and covert. Therefore they do not contribute to the purse.
Actually the ones I knew were doing care work. So they were saving the public purse quite a lot of money - ironically by helping reduce the load on the NHS (as good care work does) and by keeping the care home fees low, as paid by the unsuspecting local authority.
It's not what one would wish for - I'd rather not have illegal employment in any sector. But accusing the individual workers of not contributing is just not true. In fact, since their refugee status came through, they have continued to contribute in the same sector.