That is a very reasonable assumption. Euro emissions legislation makes it practically impossible to sell a new ICE-only car, so hybrid cars are designed to be the nearest thing while fulfilling the letter of the legislation.
There's also the various government incentives to run a HEV / PHEV.
FYI, here in tke UK, almost all Uber cars are older diesel saloons / estate cars, and mostly just a normal taxi with an extra "Uber" sticker. Talking of BS assertions, I doubt that many Uber drivers outside Silicon Valley (or maybe, to be generous, prosperous American cities) are using HEVs / PHEVs.
That’s not true in London. Most Uber cars in London are Toyota Prius hybrid cars. I would guess that’s true for >80% of London Ubers