When I drove for Uber for a brief period I almost never got cash tips. Before they introduced the tipping option in the app I maybe got tips in cash 5-10% of the time. When Uber added tipping I did find I got tipped a bit more than I did in the past and cash dipped to almost never. Now to be fair I am in Canada and we are a lot more digital when it comes to payment. I know America still has a decent amount of cash usage, but I know many people here don't carry cash on them, especially younger people.
I found that one of the few times I'd get a "tip" in cash was when someone asked if I was okay waiting for them to run into a convenience store on their way home, or for me to go to another destination that wasn't put into Uber after the first drop-off. And that worked for me, I'd much rather take cash and cut out Uber of taking a huge chunk of that extra.
