It could be the case the right now some grocery items ( not beef ) are the same or more expensive than in EU or the US, however grocery shopping is not the only monthly expense. If I was living somewhere else I guess I would take into account food, housing, clothing, utilities, health, gas, entertainment, education, public transportation, gas, etc and would make an estimate on how much living in a certain place costs against other places. I don't understand the point of just looking at this one variable.
Now just talking about food, the game totally changed in the early 90s when globalization took over and both producers and industries started to try to match their profits and prices to those of other countries, not taking into account people's income, etc. It all went downhill. Before that, food was so inexpensive that you would not even think about it, in the case of Argentina, producing so much beef, poultry, grains, fruits and vegetables, oil, cereal, etc it was very affordable.
As much as that happened, politics were unable to keep up with country development and getting more people into the job market, so now you end up having very low salaries measured in dollars and very dear prices for food, measured in dollars. I believe two things must happen: either the economy will grow with genuine investment and an abundance of jobs or food prices will need to adjust to the domestic market and then set differential prices for exports.
The bottom line is that people can restrict a lot of expenses, but they cannot stop eating. It is basic survival. As for expats, I honestly do not think anybody is in this situation, BA could be cheaper, than Portugal at time, or dearer than Chile, etc, but you have options. The real issue is those who have no options, and those with no options at times make desperate decisions.