Yep! We did this last year. Cost $8 each way to/from GF to Typhoon Lagoon. About $12 to Blizzard Beach. I would do it again. Both cars on the way back to the resort had leather seats so being damp wasn't an issue.
Regardless, I think being wet in a driver's car (outside of getting caught in the rain) is pretty rude.
The Uber drivers know they are picking up potentially wet people when they accept a pickup at the water parks. If they don't want to pick up guests at the water parks, they don't accept the fare. It's not rude.
Or they could assume that people will be courteous and not ruin their car. Either/or.
What is your issue? No one will ruin a car by sitting in it with a slightly damp swimsuit. Stop being so dramatic. I was assured by the drivers that it was fine that we were a bit damp. We sat on towels. Calm down.
By the time you get out of the water, go to your chair area, dry off as best you can, and walk to the front of the park you are pretty dry. The taxi we used had "leather" seats. Honestly, being completely dry is not a concern for me when getting in a cab, Uber, bus or my own car.
We tipped $5. I was sooo happy I didn't have to take the circuitous bus back to BWV!