I have spent a couple of nights in locked metro stations myself : before locking, they just warn that they're going to lock. Whoever's still inside is locked in until morning, but there's no kicking out.

That must be one of the bigger stations like Châtelet. There are endless hallways and tunnels to hide in. A simpler 1-train station will have 2-4 exits and they will certainly put you out.

Using subway stations as shelters during off peak hours is a masterstroke of efficient infrastructure. Every city should do that.

nope, the right would be everyone be able to have a place to live. There is no dignity in supporting the poverty.

What if some people don't want a place to live, just somewhere dry to spend the night?