Why would it be fraud? PPL are allowed to share fuel costs with passengers, even the basic Sport Pilot licence in the US is allowed to carry a passenger and let them pay their share of fuel, landing fees etc. This service just allows someone to hitch a ride and pay their share of fuel.
You can do all that even as a sport pilot in the US, you cannot though hold out (i.e. advertise your services) though without the appropriate operating certificate.
Flight-Share Deemed Illegal by FAA in Blow to AirPooler - Bloomberg Business