Since Uber still claims it's not an employer it's going to continue to not provide this, which means they'll face dual claims: from guide-dog owning passengers and allergic-to-dog drivers, both of which are being discriminated against by Uber's illegal practice.
They are independent contractors, that is a separate business entity. Which means, you're right that Uber is under no obligation to give accommodations to their drivers, since they are not an employer.
It's...not a situation I'm a fan of, but it's the current legal status quo.
Gotta love "disruption" /s
Whilst complying with the law. Self employment does not exempt you.
A disabled passenger would have grounds for a case against the "self employed" driver if that driver refused carriage, or did not stop when they saw a service animal.
> The vehicle is owned/leased by the driver not Uber
As are many (most?) taxis and private hire vehicles.
There are three questions there: is an severe dog allergy legally a disability, is the driver in a relationship which entitles accommodation (regular employment would normally qualify, being a contracted supplier of service might not), and is a reasonable accommodation available.