London is particularly notable because it escaped forced privatisation of e.g. bus services. In London all the buses are red and work the same. You do not care whether your bus is a "Big Corp" bus or a "Tiny New Outfit" bus, they're both red, they both take Oyster, or credit cards or whatever, they're the same, the bus service is controlled by Transpot for London which responds to an elected Mayor. In most UK cities by contrast there are multiple, privately owned bus companies. The local government can try to persuade them to run services it wants but they don't have to, and indeed if the local government won't do what they want they can just fold up the service and go home, too bad, the government have to contract with a for-profit business and if nobody wants to do it then too bad no buses.

Until relatively recently (things have improved in Scotland especially and now increasingly in English cities) it would have been illegal to do what London does anywhere else. My city really wanted a single card that works on a bus or a train anywhere in the city, they couldn't persuade anybody involved to actually do that and the cards went away without ever being actually useful.