Taxi can be found in the entrance of the airport. A guy nearby those taxis will give you the taxist job.

They are fast, they have 4 seats, but they're so flashy so dont try to hide in one of them.

They can also work as a method of kidnapping. You can just say you're a taxi driver and they will get a ride, then you just have to handcuff that boi. And it's done! [HAAAA, GOT HIMMMM].