Cognitive load for installing "yet another app" is pretty real. It doesn't matter how easy or seamless the experience is, part of the value for an app is to make it easier for repeat customers to use their service, and make them sticky. That starts with wanting to buy from them in the first place though.

If I'm on a road trip, and I need a quick meal, and my choices are "buy from place that makes me use their app" or "buy from place that doesn't make me use their app", I'm gonna choose the option that is more convenient to me, which is, the one that doesn't make me download anything, sign up for an account, and pester the hell out of me 2 hours after I have already forgotten about that particular fast food joint to let me know if that if I only buy 39 more Big Macs that I can get a free small fry.

I don't really want fast food to begin with. The food quality at any vendor has continuously gone downhill (or my standards have raised, could be some combination therein). If they want any hope of capturing my business still, they'll only get it if they keep that process as frictionless as possible.