The stations that carry it tend to only carry one brand to begin with. The owner of that brand is generally the one that pays, as they have to submit for testing at their own expense.

It's not always more expensive. All Costco gas is Top Tier, for instance.

They require the brand to use the 2x detergent level for every grade, at every location, to display the Top Tier logo.

I go through a tank of gas every 1-2 days. When I don't fill with Top Tier, my fuel economy goes down on that tank. When I consistently don't fill with Top Tier, my fuel economy goes down even on my next tank of Top Tier. That's when it's time to throw in a bottle of polyetheramine (Techron, Redline, Gumout Regane, etc.) to clean things up.

DI engines unfortunately require deeper, periodic cleaning, as the additive will not reach the valves. But I do not have a DI engine, so the detergent makes a significant difference.

It particularly makes a difference in how often I have to (or do not have to) replace lifters to keep them in spec. This engine has solid, non-adjustable lifters.