This is what I come here for - entertainment.
This Uber service hasn't started yet - it will start today. I would wait and see for at least several months, how it will work out with Mex customs
in SY and overall performance.
You can't predict performance for this - very unusual - route, based on their performance NOB. On Uber website you will see reviews from all over the
world, and what they have in common is - irrelevant to your situation 
You can't predict prices - their software shows , say, route from SD to TJ central bus station costs 3 times the cost of Greyhound bus on the same
route. Greyhound uses same freeway and border crossing and doesn't makes any stops other than SY station - though they won't take you to some hotel in
TJ/Ens area.
Same Uber software shows about 1/2 cost of taxi from SD to SY, and 3/4 cost of shuttle (i.e. almost same price). The article claims Uber to be
"economic" solution? I donno.... Maybe it will cost less, or maybe more, or maybe their ride won't be available 5 times out of 10.
About border stop for FMM. Buses do this, Uber will have to do the same if passenger requests. This is another thing that takes time to sort out -
they should put a box to tick on the software app.
Btw, is Gato really a "goat" or "male cat" in Spanish? |