@WrongSwanson This. Slumlords are a problem but what is probably more widespread are amateur landlords that think BTL is a passive investment, which is a byproduct of the mentality that house prices only go up and once you "get on the ladder" everything is smooth sailing.
You wouldn't live in your own home without maintaining it or having some sort of insurance so why would anyone think that they don't have to do the same in a rental property. Owning a business comes with even more risk than owning your own home. These are the people that are hiking up the rent every time there is an interest rate rise. They usually also subscribe to the view that renters are somehow less than, which is why they think they don't have to do any repairs or think they can deduct everything from the deposit.
I once rented a house with a very mature garden. It was stated in the contract that the landlord was responsible for maintaining and cutting back the large trees annually, although it clearly hadn't been done in a long time. The EA was fully aware of the state of the garden since they did regular inspections and ignored requests to sort it. By the time they got around to dealing with it the trees were so overgrown it took 3 days to do the work. I had to take time off to let the workmen in, live with the disruption and because there was no exterior access to the garden the workmen had to drag everything through the utility and garage, leaving me to clean up the mess. They damaged the cheap vinyl flooring in the utility room and despite reporting it, the landlord tried to deduct it from my deposit 😂I got an earful from the EA that the landlord wasn't happy that the work cost so much and I need to let them know before it gets so bad. Or maybe they could just fulfil the obligations in their contract? This was a pattern with these landlords. The EA would avoid passing on any requests for repairs (like crumbling tile around a fireplace which was covered up with a rug when I viewed) because the landlords were so put out at the idea that they would have to spend any money on the property.