As a local I can tell most argentineans tip.
On my trips around the world I observed many people do not tip at all. In most cases the tip is added to your bill leaving you without the opportunity to punish or reward the waiter.
Something that disturbed me in Palermo, was that many european tourists, after chewing a whole banquet would leave a couple coins on the table. When I traveled to Europe many locals felt odd about me tipping so much the local waiters (10% at most). I think tipping is not much of a custom.
Contrary to the obvious many locals from Recoleta won't tip more than the ones of Constitución. The recoletos do not get rich by tipping.