Why must it be Kowloon Cube and not any form with an intermediate density?
I live in Trollhättan, a Swedish city of about 60,000 people and don't have a car. It isn't hard. And Saabs were built here, so this isn't some sort of anti-car place.
I used to live in Santa Fe, NM a US city of about 70,000 people. I had a car, but across later visits was there for a couple months without a car and found life much harder.
Santa Fe was founded in 1610 so was a city for 300 years before cars became popular. Its population was about 5,000 in 1912, so most of the build-up was during the car era.
Trollhättan became a city in 1916, when the population was only 15,000, so again most of its build-up was during the car era.
Why does transit-oriented development make sense for Trollhättan but not Santa Fe?
When you say "small town", what size do you mean? https://en.wikipedia.org/wiki/Town#United_States says it varies by quite a bit - Alabama says a town has a population of under 2,000, while in Connecticut, West Hartford is a town with a population of 64,083.
Could you gave an example of the urbanists you mean? There isn't much need for public transit if you can walk across town in 15 minutes.
But since they really developed the bike infrastructure and cut down street parking and limited street access during the day, the city is remarkably less loud, there is a lot more people outside even in winter and the life is overall better, for me. (also we can rent electric cargo bikes for 40 euro per month, and I see a lot of those nowadays).