The difference is that at some point in your Uber "career" you will be expected to transport someone with a service animal and you can't legally refuse to transport them. The way the law is written you can't even ask to see proof it's a service animal, if someone tells you it's a service animal then it legally is a service animal to explicitly prevent this form of discrimination.

If you can't perform all the legal requirements of a job then there's a case to be made that you probably shouldn't be doing that job.

Taxi drivers can't do any of that either, so I don't see the problem.

I agree with the last part at least. What I mean is "we can have a debate about whether the current legal requirements need exceptions for eg allergic drivers".