Uber punished for 2 months last year for using a foreign credit card with a Argentine number and Argentine id. They said its illegal to use a foreign credit card in Argentina. They blocked me for 2 months in my worldwide travels.
I wrote them 100 messages and literally had to "beg" them to unblock me.
I personally use taxis ( usually) in BA..but I am a big user of Uber in Brasil ( where I travel often to) and Uber is almost 1/3rd the taxi prices there, is 100% legal and has dedicated pick up points at almost all the Brasilian airports.