For some kinds of retail businesses I do expect one price independent of the location within the country. Not for groceries, of course, but I do expect consistent pricing in Zara or Ikea.

I see no reason to expect people in lower cost locales to subsidize people in higher cost locales.

Companies that apply a nation-wide pricing scheme do see a reason, I guess.

Few retailers selling sufficient quantities of high margin goods might do it, but most need to factor in local costs such as labor, property tax, and rent. Especially once the gap in costs diverge significantly between regions.

And no bats an eye at paying more at a restaurant in SF or Manhattan.