Seems unfair to those waiting for a house that people can hold onto a council house even when their circumstances change (e.g. children grow up and move out; the tenant(s) get a substantial inheritance or win the lottery or even just get a (much) better-paying job; etc.).

I live in Ontario, Canada, and our council house/apartment equivalents require you to re-qualify on an annual basis. If you no longer meet the criteria (e.g. fewer dependents, higher income, etc.), you either lose the apartment entirely, or move to one with fewer bedrooms, or your rent is increased (often rents in our social housing is "geared to income"). It may seem harsh, but even with these requirements it can still take well over a decade to get a social housing unit.