Can I speak up for the 'private, robbing landlords' here?
I should also state that I was on the board of a Housing Association for some years and was involved in developing and letting affordable housing and shared ownership housing. So I have seen both sides of the debate at first hand.
Private landlords have to pay market rates for the finance to buy properties, and they are taxed, usually at 40%, on any profits, as well as the profits of any sale (less the usual capital gains personal tax allowances). They also have to pay market rates for repairs and VAT is added onto this. Buildings insurance is again at market rates.
Social housing is usually built on publicly owned land where the profit motive is not a factor in the housing association acquiring it, so the land is usually free (in the case of redeveloping certain areas) or cheap, as part of a larger project usually. They do not pay Corporation Tax in the same way the private businesses do. They do not pay tax on their profits, in the conventional way that a property developer might do, as profits are reinvested for the public good. They are usually fairly substantial organisations and have large teams of tradesmen doing repairs, and they are able to negotiate lower hourly rates, plus they can reclaim VAT on certain repairs. They are able to benefit from special public sector rates on buildings insurance as they amortise the risk over larger numbers of publicly owned properties. If they need finance, for some reason, they are able to access preferential rates for finance as the risk of lending to a public sector organisation is seen as comparatively low compared to a private individual or small company. Small private landlords simply can't compete with all this.
So if you take a property at £1800 a month, as opposed to an affordable rent of £600, say mortgaged at £200k, let's break down the costs of the private sector property to see where the actual differences are. I have done this very roughly indeed and left out some of the more complex overheads, but it's just a very ballpark set of figures.
Difference in cost of finance typically = £300
Difference in buildings insurance costs = £60
Difference in VAT costs on say £100 a month repairs = £20
Difference in tradesman costs = £20
40% on £1400 (typical costs after overheads) = £560
So the landlord's actually making £860 of that, £8020 a year, but has to maintain the property (sinking fund of £1500 would be sensible) and draw a salary. If interest rates go up, they might actually have to top up the mortgage payments out of the profits from previous years. The landlord also needs to budget for two months' voids a year in case tenants don't pay or there is a problem letting the property, so that's £3920 a year, or £326 actual safeish income a month. That's not megabucks for a job where you find yourself occasionally called out at night to unblock drains and so on. (Caveat: My figures may not be perfect, but they give you an indication).
I think the problem is that we need to move away from a lot of little landlords reinventing the wheel, and towards a series of larger landlords with economies of scale and more recourse for tenants should things go wrong. However since the 1908s we decided to largely privatise the rented sector, and we've made it a lot more expensive than it needs to be, without tenants or landlords generally doing that well out of it. Our private rented sector is, in short, rather fucked.