If Papa John's calls in thousands of fake pizza delivery orders to Donimos, are they doing research on response times and how many drivers their competitor has, or are they committing a crime?
The interesting thing about this example is that literally both of those specific companies (and other QSRs with online ordering) are actively researched by hedge funds this way. You can uncover a truly magnificent amount of data by doing this with, say, their mobile apps' private APIs.
I have no idea if they do it to each other though. I'd guess not.
To make this comment even more meta: I leave it as an exercise to the reader to figure out how you can use this technique on Uber to get competitive intelligence about, for example, how many total restaurants are currently signed up for UberEats, how many have ever signed up and the rate at which more are signing up in each region. The UberEats mobile APIs offer a way to do this, though individual restaurants use non-sequential UUIDs; do this every day, break it out into a timeseries, and compare it to GrubHub. Voila, you've turned their game against them.
They'd probably still be charged. Also dominos and papa johns and even Pizza Hut don't compete in delivery zones (unless there is so much demand for pizza that it doesn't matter). The losers are the local shops. Prices are nationwide which is where the competition is. They really just want people to order a pizza delivery.
Unless your are in New York but I guess that local pizza wins. Maybe a few downtown areas as well.