Your example for small town does not work in an economic model based simply on sales, payroll, and taxes. It provides convenience and lots of low quality low priced products being spread around, but it is not economically sustainable long term.

Case in point.

Retail jobs have always had a sales per payroll hour goal. The store wants to sell so many dollars of product for every payroll hour they use.

At a larger clothing store I worked at, it was a goal of around 160.

At a book store, it was 80.

At a sunglass store, it was 30.

Added together, those 3 stores would use 1 payroll hour to generate $270 in sales.

What's Walmart's goal? I haven't worked there, but I'm betting it's over $1000 per payroll hour.

The big box effect reduces payroll dollars, thereby reducing payroll tax revenues, while increasing employment in uh, well, other countries. They contribute to their profits and they contribute to the global economy, and they provide us with an excellent reason to practice the very spend thrift consumerism that politicians like to keep us occupied with so we don't vote all of the morons out of office.

This is not sustainable. Eventually, we'll run out of decent paying jobs to provide us with the money to buy the cheap crap. And again, as I said, just because you build a Walmart in a small town, doesn't mean the residents have more money to spend, just somewhere else to spend it. Urban sprawl is terribly inefficient.