It really just depends on who you get at immigration upon entering Argentina. I printed out my ticket to Uruguay, had everything ready, and all the immigration guy said after barely glancing at my passport was, "Bienvenidos a Argentina!" He said nothing of the fee even when I asked him explicitly.
However, I have a friend that was held up for about 2 hours until they decided to let her off with a very limp, slap-on-the-wrist warning telling her not to overstay ever again.
SO there you have it --2 very different scenarios.
I don't think they'll ever NOT let anyone inside the country, especially because they're not posing a huge threat. But maybe I'm just being naive, who knows.