I hope you’re being funny. Nobody knows how to text while driving - everybody is a hazard on the road when they’re paying attention to things that aren’t their driving.
I’d start by taking pictures* of him texting, his cab license, the cab number, whatever else, and complain to his company later (if he didn’t stop doing it while he was driving me - I don’t want to end up wrapped around a tree because of his law-breaking).
Take out your phone and start rolling video. Demand the driver stop texting, if they fail to then demand the driver stop the car to let you out. Regardless of the outcome, complain to the cab company and whatever form of taxi and limousine commission has jurisdiction over the driver. The phone number should be prominently displayed near the driver’s ID badge.
Driving a taxi requires a commercial license with a passenger endorsement. It doesn’t matter if you’re in some hick town that doesn’t have texting and driving laws, texting while operating a commercial vehicle is a federal offense carrying up to a $2,750 fine for the driver and up to a $11,000 fine for their employer. I know for a fact semis and tankers and busses are included, I’m not 100% sure if taxis are. It’s still dangerous as hell.
“If you don’t like the way I drive, stay OFF THE SIDEWALK”.
I found the remark funny (and yeah, Cat Whisperer, you were whooshed!).
That said: Concur on taking photos and asking him to stop, though of course it’s too late for that now. But report it to the employer and whatever local taxi commission there may be. This guy needs to be up on disciplinary charges at the very least.