Well I didn't just get the impression from them, it was from watching the show in general. Cabs have often been an issue, one that I feel doesn't add positively to the show. When they get lost on their own it's funny, when their cab driver gets lost it's just annoying. They did say in the interview that all teams had trouble with cabs and that they had to switch cabs a few times because many were broken.
Something else interesting that they mentioned was that it took a long time to get the camera and sound crew into the cab as well. If they had their own cars this wouldn't be so much of a worry.