These are all places with heavy handed rent control. They are so caught up in the hate the evil landlord concept that they don't realize that residential property is not nearly as lucrative of a business as they think. Most of the value comes in potential growth of equity and paying down leverage (i.e. paying the mortgage). When subtract loan payments, taxes, and operating costs from rent there's not much left over.

Rent control, eviction moratoriums, etc. only limit the income to the owner more. Less income equals less money and incentive to do any improvement. I have residential rentals and I wouldn't touch property even near a blue city, it's not worth the trouble.