You shouldn't have issues at Western Union I wouldn't think unless something is new. I don't know how they would know how long you stayed here. But you are right the supermarket lately is asking for passport. You shouldn't have issues in USA.I posted in another thread but maybe more appropriate here.
I'm asking for a friend. Let's say you are from the United Kingdom and you have been illegally living in Argentina since 2019. You didn't leave to Uruguay to do border runs as you heard that it was better to overstay and just pay an exit fine. Let's say lately at the supermarket they are asking for passports all of a sudden and you go to Western Union today and while they are scanning your passport they call the Manager over and they are talking and flipping through your passport. I didn't get any stamp in my passport when I entered Argentina so I don't think they know when I entered but they saw my exit stamp when I was leaving Europe and they were asking me some questions.
Will I have any issues going into other countries like the USA. Will anyone know that I'm a criminal and overstayed in Argentina. Will I have problems coming back in Argentina in April?
Only asking for a friend.
I can't answer if you will have issues coming back to Argentina. For sure they will know you overstayed and will have to pay a fine. They might hassle you that it's been YEARS. (I mean your friend stayed years....). Ha.