The lack of trust between taxi driver and taxi passenger ruins phone call hails. Once in Austin, I called the dispatcher for a pickup, waited for 2 hours while calling every 15 minutes and being promised a ride in 10 minutes, eventually gave up and walked 5 blocks to a major intersection and immediately hailed a cab off the street.

Since taxi passengers can't guarantee they'll get picked up, a taxi passenger will sometimes call multiple companies or pick up a random cab from the street. Since taxi drivers can't guarantee the passenger will be there upon arrival, they will pick up any random person along the way.