If someone is found out to get there, escape, and get there on and on, then it's a criminal offense (sounds like 'systematic homelessness') then they are sent to normal gulag-style forced labor camp (as in Russia, there are almost no prisons as such in Belarus, almost every institution which looks like prison is in fact a jail - people are kept there only prior to being sentenced).
That system sounds like well-balanced and fair to me, even if is not perfect. Being a (chronic, i.e. semi-permanent or permanent, as opposed to someone who just happened to get in a tough life situation) homeless, is an obvious crime against public order. Crime difficult to effectively punish without resorting to terror, and yet a crime. Belarusians have built a well-balanced, working system which lets good law-abiding citizens feel safe in the streets.
Or consider how easily you could end up “useless” for society: if you get cancer, or into a car accident, would it be ok for society to just let you die? After all, the treatment is certain to cost far more than the taxes you would eventually pay after recovery.
I also feel quite safe here in the streets of Berlin, and part of that is that nobody is going around dividing people into useful and useless.