How about people who have been given leave to remain. Are given Social Housing. Never live in the house.
And get full Housing Benefit.
Then sub let it to one or more of their friends who are here illegally, or overstayers on short term ,low skill work or student visas.
Or use the place as a business address to run a fake or dodgy business. Think pop up Vape shops and short lived take aways.
Before l am flamed for being racist. I can testify that this does actually happen where l live. On a regular basis.
Or alternatively they use the flat as an unofficial Airbnb for overseas visitors from their country of origin. They also take long holidays, over a year and more in their country of origin.
You know the country where it was so dangerous to live in.
They had to flee for their lives
When Housing Associations are told about these practises by other genuine tenants.. They will say that the tenant in question is doing nothing wrong.
This means they couldn't care less because the rent is being paid. And that is all that matters and they care about.
You can always check with the electoral register to see who is supposed to be living at a certain address.
I have lived on my particular small HA estate for nearly 40 years..And believe me. I have seen many instances of these sort of activities.