As Oxford is mentioned here. And I have lived there mostly since the 70s (born in 70).
It is worth noting the city has a history of trying to control / prevent folks driving. So much of the city is listed that doing so is sorta fair. But there has been councils and opposition to them. Trying traffic management schemes since the late 70s. Way back in my younger years. My brothering law was a student. Whos professor was responsible for developing the oxford one way system in mid 70s. He did so with the intention of discouraging driving. As that was tghe main concern of the council leaders of the time. And throughout my life oxford has done more and more to discourage traffic entering the city.
Personally my vision means I can no longer drive. But having had to face rush hourtraffic down the narrow streets in the 90s. My only real complaint was how bad at it they were.
But the reason I bring this up. The 15 minute city idea. Is just a new idea the Oxford councillors use to try and sell the ideas they already had.
As someone legally blind now. Gowd I wish most essentials could be within a 15 min walk. When I need to get to any hospital appointment. Its normally 1-2 hrs by bus. Rush hour of the 90s. Really is all opening times in parts of the area these days. The idea of 15 min cities is a good one overall. The issue is that 13 years of austerity means no city can really make the investment needed for it to truly happen.