> ADA is a federal law, so I don't think it would make any difference within the US in different jurisdictions.

ADA applies to employers for their employees disabilities, and providers of goods and services for their customers disabilities.

In a jurisdiction where Uber is a provider, the driver is an employee, and the passenger is an Uber customer it may well apply differently than in a jurisdiction where Uber is a third-party-matchmaker-service, the driver is a provider of service to the passenger, and the passenger is a customer of the driver that locates and pays the driver through Uber services.