It's grim.
As a Landlord I am on the other side, and have just let a three bedroom Victorian house to 3 recent graduate sharers.
Rules and regulations have tightened up so much that it is difficult to keep track.
Not just the standard EPC, EiCR, and Gas safe. But the government has essentially foisted residency and money laundering checks on landlords and are about to introduce new tenancy legislation which, though designed to help give stability to tenants, increases risk and reduces flexibility for tenants.
The Local Authority has jumped on the bandwagen and suddenly introduced some sort of additional/selective HMO licensing, charging me about £1,500 simply to check I have the certificates I am supposed to have as well as a copy of my landlord insurance. The insurers for their part increase their annual quote by £2,000 because the property is now an HMO, whilst the letting agent also decided to get in the act by charging me a £150+VAT HMO fee. The certificates could be checked electronically and there is lots of existing legislation to cope with landlords letting poor quality accommodation. It is hard to see it as anything other than a means of raising extra revenue.
In the end tenants will pay. In the past I have been willing to let to two singles and a couple to help keep individual rents down, but can't till I know what I am licensed for. Licensing requires I have insurance, insurance requires tenants to pass affordability checks. I used OpenRent for the first time as the £150 HMO fee demanded by the agent (Foxtons) was a step too far. I normally try to keep rents moderate to allow for a better tenant choice but also wanted to avoid attracting too many applicants. Embarrassingly the market rent was 50% higher than I was getting two years ago. Even so for first viewing I had six groups including: actuaries, investment bankers, accountants, lawyers, land agents, solicitors and more. No need to look at people who needed guarantors or those on lower incomes. In particular I felt sorry for those from overseas who were offering six months in advance, something that is likely to be banned under the new legislation. I also felt sorry for the group of post F2 doctors, who were on one year temporary contracts. (DD is at the same stage, and facing unemployment in a week's time, so understood the naivety of grabbing any job without checking if they could afford to live in London and failing to understand they needed to be quick.)
It gets worse. By 2028/30 legislation requires me to bring the house up EPC C from EPC D. This will require major works and major investment. It can't be done with tenants in place. Builders are in very short supply in Central London (because they cannot afford to live there). Even if I could find people to do it, it would be difficult to raise the money, so I will have to sell. So despite huge demand and rapidly rising rents, there will be one less (more than one, as a lot of rental property is Victorian) house available to rent.
I liked Open Rent but it was very structured. Applications, references etc had to be in their format. This ensures that they carry out the checks according to the law, but does not allow for the sort of exception OP is hoping for.