> It seems like the least controversial thing that the left and the right should have agreement over: rich people not getting subsidised social housing.
The argument I've heard in Germany is that it's a good idea to have more socially mixed housing projects, so people who moved in as students are allowed to stay when they work full time. Initially they had to pay an extra fee ("Fehlbelegungsabgabe" = erroneous occupancy fee, but even with that it was much cheaper than regular housing), which was removed at some point.
Our social housing stock is already intended to be mixed (although the balance is often not great). You'll often find social and non-social housing units in the same apartment building, and definitely in every neighbourhood there will be a mix. I agree and think that mix is super important. But achieving it by giving rich people subsidised housing when there are poor people on a waiting list for these units, is one of the least optimal solutions, compared to alternatives.
The argument I've heard in Germany is that it's a good idea to have more socially mixed housing projects, so people who moved in as students are allowed to stay when they work full time. Initially they had to pay an extra fee ("Fehlbelegungsabgabe" = erroneous occupancy fee, but even with that it was much cheaper than regular housing), which was removed at some point.