Employers of cleaners pay less tax (but they pay NI contributions instead - probably roughly the same amount)
Cleaners only pay tax once they reach the threshold
Cleaners no longer receive benefits, as now earning a salary
Cleaners also now have proper sick pay, maternity pay, pension rights etc.
So the state is taking in a similar amount (but as NI instead of tax), unless the cleaner is earning pots of money (in which case they shouldn't have been on benefits anyway, whilst earning all that cash-in-hand!) = cash neutral for the state
Employer pays roughly the same in total as before = cash neutral for employer
Cleaner now has decent social protection, whilst in most cases still not taxable = cash neutral for cleaner
With the bonus that no-one is working illegally, the poorest workers now have the same rights as other workers (sick, maternity, unemployment...) and the official unemployment figures no longer include those claiming benefits whilst actually working! Those only working a few hours a week may still be entitled to certain benefits, but it's a good way to get people back into the workforce!