I always found the difference between Argentina and Brazil quite surprising. While I lived there (for seven years, in Santa Catarina) I felt like people were very divorced from politics, and would avoid the topic as much as possible. The only people that would engage me when I asked questions about politics (mostly because I wanted to learn the history of the country) were people from bigger cities (mostly Paulistas.)
Argentina went completely the opposite way: once the dictatorship was over, people became incredibly political because we wanted to avoid the same kind of political vacuum that created the first coup. As a result, most people in Argentina will argue about politics, even when they don't have a completely educated opinion on the matter (but hey, that's how we work on most stuff anyway, heh.)
Agreed on the conflation of lobbying with bribing. Unfortunately there's too much evidence suggesting that private interests putting money into politics is not a good idea.