They don’t have to work, you just have to convince people they do.
Sell the gas station operator on increased revenue (whether they ever see increased revenue from it or not is irrelevant — I would assume they are unlikely to stop once they have ad pumps in). They might not opt for ad pumps next time, but that’s a problem for future you.
Sell businesses on thousands of people staring at these pumps every day.
All parties are now invested in this ecosystem, and it’ll be a while before they determine whether or not it’s worth the money — or even having an effect.