Cab drivers would have to drive safe and keep there calm more then common drivers.
There are some crazy ones, but for the most part they're the main culprites not changing lanes and whatnot. Longer ride = more money. It is frustrating. You can usually tell them to step on it if it's in a hurry. I had a massive dump coming on one morning and still had like 10 more minutes 'til I got to the office. He was cool, and ran some yellows and whatnot. He got to keep the change which was upwards of 900 yen or so.