Owning a rental house is not the simple business it once was.
For instance,
There is a whole industry of Real Estate agents managing the rental, taking usually 7% of the rent. They promise to 'protect the value of the property', and protect the interests of the tenant. I have not heard any glowing reports of value for money.
There is a notable lack of general care by tenants on the assumption that the landlord is getting rich from the rent, so the wear and rear is worse than that of an owner occupier. Also, many young renters simply have no idea how to look after a property.
Remember, a house is not rentable until it is brought up to a set standard, but the overheads continue to cost the landlord until it is once again rented out.
Nowadays there are extra costs for regular testing of safety switches and fire alarms (every 6 months?).
There are no cheap rentals nowadays for the poor. For instance, when I first married, we rented a tumble down house with an outside toilet, with no light. It was rough (non tenantable in modern rules), but we went out and bought paint and spruced it up. Later we moved to better places, but it was common to run a paint roller over the walls to make it look a bit cleaner than it was when we moved in.
Modern tenants wouldn't dream of this.
The result is a shortage of cheap rentals.
I had two rentals, one made nil capital gains for seven years, the other made a capital gain. Meanwhile, they just broke even, whilst being a constant pain in the arrs. My experience is that about one tenant in ten was good.
Sure, the developers and big players seem to get rich from it, but not the smalltime investors.