But, as has been said (by me and others) maybe they can't find a mooring near their work and/or school; maybe they can't afford a mooring in that place. They have taken to the water as, possibly, a last resort to either no home or B&B or expensive poor rented accommodation.
As I said I don't have the answer, I just feel/hope that there is a better answer out there that doesn't involve just taking their home and displacing them and their kids. If they simply refusing to move on shear bloody mindedness (no kids, no medical reason) then the picture changes and enforcement is probably the answer.
Bob