These stores have massive invisible subsidies in the form of tax breaks and infrastructure built to support them. That's a huge factor in how they're able to undercut local shops. The city is really footing the bill.

A local butcher shop takes up a tiny amount of area, and therefore a tiny amount of infrastructure. It pays way more in taxes than Wal-Mart, compared to the amount it costs the city to support.

This is a central part of the strong towns message, about why our towns and cities are all going broke: https://youtu.be/K0AZXUWr_Rg?t=3723