Solving the chicken an egg problem could be difficult, you may try partnering up with car services or cab companies
You could look into car services instead of cabs..some times these types of services will have specific routes/destinations planned..making it easier to match people up..a possible problem is people not wanting to share a car service though.
You could also look into partnering up with cab services that constantly service airports. you could set it up where someone could use your app to set up a cab ride prior to taking off at another airport. That way cabbies will have passengers set up, instead of having to sit and wait. you could pair people up who are coming in at similar times to share the cabs.
Just thinking out loud. I'd love to talk to you more about the app, I've been looking into developing an idea that involves pairing people up to share cost. (not related to your idea)
You could look into car services instead of cabs..some times these types of services will have specific routes/destinations planned..making it easier to match people up..a possible problem is people not wanting to share a car service though.
You could also look into partnering up with cab services that constantly service airports. you could set it up where someone could use your app to set up a cab ride prior to taking off at another airport. That way cabbies will have passengers set up, instead of having to sit and wait. you could pair people up who are coming in at similar times to share the cabs.
Just thinking out loud. I'd love to talk to you more about the app, I've been looking into developing an idea that involves pairing people up to share cost. (not related to your idea)