It's a bit unclear exactly what the 80 % figure measures, but according to TFA it's the lower bound of the fraction of people who got housing fully subsidised a

It's a bit unclear exactly what the 80 % figure measures, but according to TFA it's the lower bound of the fraction of people who got housing fully subsidised and is now pays their rent independently. Given that the homeless include people with serious problems, that only at most 20 % need ongoing subsidising sounds like a huge win to me.