There is a big difference between individual taxi drivers refusing to take a specific fare at a specific moment in time and a company that controls a large percentage of ground transportation denying someone access to it forever.
It's like the difference between an injury and a chronic disease.
No, I think they should be fired and not allowed to work in public transportation for some time, and only then after some rehab/training. People can change, after all. But this is a different issue with different sorts of solutions.
It is really more like having one cashier at a grocery store refuse to ring you up as opposed to the grocery store chain not allowing you inside because the cashiers decided you weren't delightful enough, even if that was because your child was loud a few times.
When it is the cashier, you have a bit of recourse, after all. When it is the chain, you have very little recourse and not only that, but now you have to figure out where else to shop. It might not be so bad in a town with many grocery stores, but it'll be mighty inconvenient if you have to drive to the next town to shop.
It's like the difference between an injury and a chronic disease.