When a central door is fitted the wheelchair access is normally through the central door due to logistics with the interior created by the central door. The layout between single and double door buses are quite different.

Most central door buses can’t use bus stations as wheelchair users have no way of accessing the bus, due to the platform length not reaching the centre door.

 

Historically, might it be because the central doors proved something of an incentive for fare dodgers in the past?  On a crowded bus and away from the eyes of the driver it would certainly present such opportunities especially in the days before onboard cameras were commonplace.

 
My experience in Bristol is that dwell times are a lot longer than they used to be - something that the Guardian article did not refer to, perhaps because it's less of a problem in London.

Passengers are now told not to get out of their seat until the bus comes to a stop. I can understand why this is - it's plainly safer - but coupled with the time taken to tap out, it can be quite a while before everyone who wants to get off has cleared, and only then can passengers start to board. The Metrobus vehicles have a central exit door, something which was common on city routes in the past. Can't help wondering why this is not a feature on other city buses?
 

 
The conclusion of the article touches on successful new bus routes that provide for changing travel needs, but what the answer is for people who will not consider a bus or are totally unfamiliar with the concept I don't know. Staying with friends in the suburbs I was shocked to find that despite living there for twenty years they didn't know where the nearest bus stop was to home, or where the buses ran to - and I recalled at one point that the school run had imposed on them a daily journey that was more than a little insane and could only realistically be done using a car - but that had been their choice. If people do experience the buses at morning or evening school run times, depending on the route, they'll more than likely get the message that fare evasion is endemic, something that lowers the sense of personal security.

 
Quite a long article here, detailing how cycle lanes, road works, traffic and many other factors are slowing down buses in London and elsewhere:

https://www.theguardian.com/uk-news/ng-interactive/2026/sep/23/london-buses-in-terminal-decline-why-public-transport-in-global-cities-is-slowing-to-a-crawl-visualised