The problem with your comment is that you are wrong in your interpretation. Your interpretation is that it's black and white on what the FAA can do. There's famous saying among pilots when doing something that isn't explicit in FARs. "That sounds like a grey area". For a conservative pilot, they'll never do it because it could be a license suspension or at minimum dialing a number to talk to an FAA investigator. To a more liberal or adventurous pilot, they might bend the limit and see if it comes up.

I am curious if you're a pilot and if so have your CPL or ATP.

It's not about the PPL vs. CPL (and by definition they need more than a CPL). The difference is in what might be considered "compensation". The FAA's interpretation of this is so incredibly broad, it should scare the pants off anyone considering bending the rules here, and their lawyers should have picked up on this. Did the flights with vendors increase a relationship that might further an interest or negotation later? Did the flights help them improve their app? Did it result in a prospect of a return favor?

It may not be fair or just, but the FAA put those rules out there and a whole lot of people have been inconvenienced by them. I love that Tapjets is doing this, but they moved fast and not particularly wisely. If they thought they could run like Uber and ask for forgiveness later, they never worked with the FAA.