If you are working as a commercial driver or employing commercial drivers then yes, complying with the law is very much "your fault".
Letting your dog loose in your own car is your own choice, but the trunk exists for unsecured cargo so in an accident, you don't have large objects flying around inside the cabin.
The correct solution would be to identify the handicapped passenger with animal and dispatch an appropriate vehicle. Instead, Uber puts both driver and passenger in danger with this policy.
A van with a carrier, or an SUV with a partitioned front/rear would suffice. Instead of calling Uber X, you call Uber Furry or somesuch.
I am not completely wheelchair-dependent, but I cannot get into a tall vehicle (like an SUV). Last time I used Lyft, I had to call a vehicle and just cross my fingers that I would be assigned to one that would work for me. If not, I had to cancel and try again. I would much rather have a special vehicle dispatched to me than be assigned a vehicle that is inadequate.
The only way this is generally true of privately-offered public accommodations covered by ADA is that the requirements impose additional costs on business which they pass on to all customers.
> I doubt that Uber subsidizes the additional cleaning for transporting a service dog.
The occasional need to do so is a cost of doing business which should factor into the minimum rate that drivers are willing to accept. No specific subsidy should be needed.
The other issue is that we, as a society, subsidize the additional cost for the handicapped; I doubt that Uber subsidizes the additional cleaning for transporting a service dog.