This already exists. It’s called Skyüber. It is not affiliated with Uber. However, it hardly has any flights, and is not at all consistent in offerings.
A similar app could focus only on specific markets. A more targeted approach could provide a stronger launch point.
A concern is the highly regulated flight industry. I imaging there is a real possibility this is not allowed. However, I believe regulations are looser around light aircraft.
BlaBlaCar is a popular ride sharing service in Europe. Unlike Uber or Lyft, it specializes in long distance trips. This service does not exist in the USA. I simply propose that it be copied.
One problem I foresee would be the higher vehicle ownership rate in the United States. However, the ability for individuals to relax instead of driving themselves may be appealing.
Would any of you use a service like this and for what length of trips?
Are there legal consequences to copying a service?