It’s exactly the opposite of that, actually. Higher elevation reduces the need for octane. That’s why in Colorado, regular is 85 instead of 87 like lower places.
https://www.slashgear.com/1825420/colorado-85-octane-gas-reason-substitute-87/
Basically just the price. I told them I was allergic to paying MSRP and that my family and children would no longer respect me if I did so. They let me walk out the first day but a couple days later reached back out.