A further data point: I'm in Cabo right now and Uber is almost unusable in Cabo proper. I had multiple canceled rides yesterday, and one successful one. It reminded me of how Uber functioned in NOLA in the first few days of launch. I wouldn't rely on Uber being available just yet.
I couldn't get Andale to work as an on-demand alternative, but I'm trying the pre-reserve feature today and will report back on how it works.