Weird. I’d love to understand the business model and how it makes sense (for the app company, not for you). Always skeptical of stuff like this.
I assume the selling point for the early adopters (among gas stations) is that it'll send them more business. Once some of them are participating, everyone else has to for fear of losing business to those who are.
From the point of view of the app company, i assume they're get some small affiliate fee of a fraction of a percent for every purchase made on it (from the participating gas stations where the sale took place).
So essentially it's a clever way for the app company to get a small cut of all gas sales, while the gas stations unwittingly get sucked into a price war.