Oxford Council is acting as though certain roads are the property of those who live nearer those roads, which is not right. And as pp point out, this isn't the concept meant by the 15-minute-city. If anything it would fit the concept far better to ban people from driving anywhere that IS within 15 minutes of their house.
And I'm with denishhol, if they want to discourage driving they need to make sure the essentials are actually available in every neighbourhood first -- start with the carrot not the stick. But since "the essentials" are not just milk and newspapers, but also as many pp say included jobs and schools, I don't see how it will ever be possible to put everything within a 15-minute radius. The whole point of living in a city is to have access to the wider range of people and culture you find there. I for one would consider having a bookstore nearby essential but that isn't the case even though I live in central London. (And yes, I do take the bus to the nearest ones ... very frequently 😉)
Also, provide more public transport. NOT just cycle lanes, which don't work for many of us -- the elderly, those with small children or luggage, the disabled, those in hilly areas, and indeed those of us who just can't arrive at work wet or dirty or sweaty... not to mention those of us who live in a country where it rains regularly, ie all of us. Here in London because TFL is bankrupt (unlike most global city systems, it gets its funding largely from ticket sales, and Westminster doesn't want to subsidise post-pandemic), we're actually seeing bus numbers deliberately CUT right at a time when every borough is putting in savage low-traffic-neighbourhoods, not to mention the ULEZ. So short-sighted!