I'm a private pilot / IFR with around 250 hours of pilot-in-command time in single engine planes (I'm guessing that's square in the middle of this company's target pilot demographic). I have a full-time job and fly recreationally. On numerous occasions I've flown friends and relatives e.g. from Palo Alto to the LA area and asked them to split flight costs. Also, while I've never done this personally, it's pretty common for pilots to seek out other pilots on message boards and the like to "split time" on some flight, where cost is split and both pilots can log some flight time.
So on the one hand, if this app were just an enhancement of that same basic pattern ... I'm flying to LA who wants to look down at I-5 traffic from 4500 feet ... then I would think it's great.
The problem is that this service is clearly intended to be more than that. And when you start getting customers who don't understand general aviation and have expectations that my Flyte(?) will run like an airline (or at least air taxi) when it will not be, you have a bad situation.
To give one concrete example, once after promising to take someone on a tour of the golden gate bridge area, dragging her to the airport, doing a pre-flight inspection, and taxiing all the way to the runway, I made a last minute decision to cancel after a new weather report freaked me out a bit. She understood, and we rescheduled. If the person next to me were not a close friend but in fact a "paying customer", perhaps business person with a meeting that afternoon in LA, would I have felt pressured to fly into an unsafe situation? Probably! This is one of several scenarios where the service just seems like a bad idea, from both a pilot and passenger perspective.
I really hate being on the side of 'regulators' in any dispute, but flying is meaningfully different from driving a car. General Aviation already has a reputational problem with sloppy, low-experience pilots putting themselves and their families in danger, and frankly I don't think adding unwitting customers to the mix is going to help the situation at all.