Small city: everything is in walking or cycling distance, there's little congestion. Big city: distance between points of interest is large, there's lots of traffic and congestion, people complain about public traffic, and take an hour to get from place A to place B.
This is my experience, having lived most of my life in small places (ranging from a monastery to a city with 25k people) while listening to people in big cities complain about their commutes.
Now I live in a city that isn't exactly small but not huge either. I'm already suffering the consequences of traffic and longer distances. Moving out of small cities is when I started to actually need a car... of course having more people and congestion doesn't show up in traffic only; it's also in the grocery store queues, restaurants packed full, parcels not delivered to home because they're too busy to deal with everyone personally, etc.
I've lived in places ranging from 20k to big cities. All base necesseties were in walking distance where I lived in the cities, and mostly in the smaller places as well.
The thing with smaller places is that you can generally get like 80% of what you need locally, but on occasion you have to go a few towns over or into the nearest city to get that 20%. So you can easily live in a city w/o a car, but it's substantially harder to do so in smaller places.
I don't believe in that 20% being a problem. I mean you can take a bus / taxi / train / buddy to get you to the next town if you need to be there. If you need to transport stuff, then you might need a car, but it's not like you would be transporting that same stuff without a car in a big city. So you need the car there too.
Also, my experience is that the 20% is more like 1-2% (when I lived in smaller cities, I needed to visit other towns or bigger cities a few times a year).
Like I said, I started needing my car only after I moved out. As a matter of fact, I only got a car a year before moving out, and I only got it because it was given to me for free.
This is my experience, having lived most of my life in small places (ranging from a monastery to a city with 25k people) while listening to people in big cities complain about their commutes.
Now I live in a city that isn't exactly small but not huge either. I'm already suffering the consequences of traffic and longer distances. Moving out of small cities is when I started to actually need a car... of course having more people and congestion doesn't show up in traffic only; it's also in the grocery store queues, restaurants packed full, parcels not delivered to home because they're too busy to deal with everyone personally, etc.