I am familiar with what the grandparent is referring to, having spent a decade running purchasing teams in US grocery stores. Even in urban areas with many different food retail stores, a typical supermarket in the US is a fairly difficult place to shop for someone with specific food sensitivities. Hopefully folks here who live in the SF Bay Area appreciate that it's a total outlier in both the diversity of stores available and the assortment of products sold in a typical Bay Area supermarket
[1] https://ers.usda.gov/data-products/charts-of-note/chart-deta...