Correlates loosely. From a product standpoint, the Falcon's hotdog is awful because they want it to be crazy cheap so they will win this comparison every year. Bears is probably the best because they use Vienna.

No idea why Buffalo is so high, but Vegas and the two LA teams are just because the city is expensive.

Actual served quality will vary quite a bit. A lot of basic concessions stands tend to be operated by volunteers fundraising for organizations. You'll get a soccer team or a sorority operating a stand. Some will do great, some horrible. The other leagues have a lot less of that because more games means more events for people to work. It's hard to fully staff a football stadium for eight nights a year with real employees.