> What dense city with a thriving commercial and business/industrial base is cheaper to live in than a less-developed rural small town?

Wrong question; dense cities with thriving economies are more valuable, so they should be more expensive. The question is who collects the rent? Land title holders, or builders and value creators?

>What dense city with a thriving commercial and business/industrial base is cheaper to live in than a less-developed rural small town?

Um, any city whose residents want services? Does your rural small town need a plumber? That plumber can offer lower costs if there's a wider, more predictable userbase for him than in the small town.

This applies to any store selling specialist goods, too - if the small town only has a single store, which stocks something that's only bought once a decade, then the buyer pays the cost of the good plus an entire decade's worth of interest. If the city can have a specialist good that sells that stuff one a month, then it'll be cheaper.

If you aren’t buying something frequently, you drive to the big city when you need it, or you order it. Most specialist goods just aren’t available in a small town same day at any price.

Plumbers and other non niche service providers are also generally cheaper in small towns because cost of living is higher for the plumber too, all potential customers have less disposable income, and because the market isn’t perfectly efficient.

Housing and basic necessities like groceries are so much more expensive in thriving dense cities than in rural small towns, that they swamp out any costs for the vast majority of people.