I think you are confusing inflation, which has made prices go up, with world prices.
Certainly, many many things are MORE expensive in the USA, while some things are cheaper.
Limes, for .40 pesos? I just bought limes yesterday in the USA, they were .79 ea- thats about 3 pesos each. I also bought some meat, $8.79 US a pound - thats what- 50 pesos a kilo?
The prague prices quoted are a tiny fraction of what I pay when I am in the USA.
Some things are cheap in Argentina, some things expensive.
Same thing with most any country, but, overall, if I skip expensive imports, and eat local, I eat cheaper in Buenos Aires than in the US.
Handmade fresh pasta in the USA is really really expensive- I have 3 choices within 2 blocks of my apartment in Buenos Aires, and all are at most 1/3 what I pay in the USA.
Beer and Liquor are very expensive in Argentina, but I suspect a good part of that is taxes.
But meat, and vegetables, are often much less than I pay in el norte.
Of course, the trick to reasonably priced, good food, anywhere, is eat local.
Any food that flies on an airplane costs a lot no matter where you live.
And any food that is gourmet, ditto.
My local goat cheese, from two miles away, is now up to around $24 US a pound- thats a two hundred pesos a kilo.
Copper River Salmon usually debuts at $24 a pound, flown in from Alaska- compare that to a bife de lomo.
Inflation, in local currency, is the big problem, but, in real dollars or euros, a lot of food in Argentina is still pretty cheap by world standards.
Mate up here is many times more than a measly 9 pesos a kilo- a half kilo of mate here would run at least 5 times that much money. They sell mate in teabags, and it costs something like 40 pesos for 30 of em.