Uber is a licensed dispatch operator in Ireland so it has the same obligations (or lack thereof) as every other taxi firm. Unlike Free Now, Uber only uses licensed taxis to cover it's taxi fares in Dublin so it probably has some WATs on it's fleet.
It does use hacks (known as PHVs) in London, MfH. However, they're a cut above run of the mill mini cabs. I used a couple last week myself, selecting the cheapest option i.e. UberX... both were pretty new Mercs, one a diesel/electric hybrid but I believe Priuseyes are also commonly used on it's fleet. I was also in one of the new remodelled TX4s and one of the new(ish) Vito hackney carriages (metered taxis) too... way more space in the Vito, beats the TX4 hands down IMO... surprised it meets the turning circle requirements.