There are multiple social mores at play in different milongas, and they don't all adhere to some universal, common, accepted, tango códigos - thankfullyWell, I think this is all just a matter of convenience. Everyone pursues their own interests and comes up with appropriate social rules.
But on taxi-dancers, a friend is shortly going to South America and has arranged some tango-time as part of a group in BsAs. That includes a pre-booked taxi-dancer for the milongas she's visiting - like arranging a guide. Sounds a good plan to make the most of her time there.