I'm just hearing the concept of 15-minute cities, and in a nutshell, I'd say it's living in Europe vs living in the US. I've not spent time in the US, but I know there is no walking culture there. For example, here in the UK, (Leicester since I'm most familiar with that city), is a big-small city where you can walk along canals seemingly in the countryside, with just a staircase and exit, and you're right in the heart of the city. You could then visit museums, supermarkets, malls, and banking and do everything on foot across the city. Most cities are actually like that. My husband who has dual citizenship and was born in the US keeps saying that some cities across the UK are slowly (scarily) starting to feel like the US, where you have to have a car.
The Netherlands is another example, where one can cycle and use alternative modes of transportation without the need for a car...
All these things make it convenient for an off-grid lifestyle.
Living on a narrowboat here in the Uk is like the closest one gets to being off-grid, in that each boat has a water tank, there's waste disposal (eaten food, garbage and all that pleasant stuff), supermarkets situated close to the canal routes, as well as Marinas where boaters can fill up diesel and purchase boat supplies. It's a different slow life on the canals, going at 3 miles per hour. Mooring up and going into some cities make you feel like you're living in two parallel words, when the reality of hos fast-paced and how much people are caught up into consumerism...
I shall cut this comment short and not turn it into a mini blog, as I'm having my first cup of coffee :)