This is true....but ONLY if you´re hitchhiking on a federal road (they are marked BR). I was stuck in Cascavel for four days asking at a gas station on the BR. I also tried waiting on the side of the road with my thumb out. Nothing.
Yesterday I got frustrated and picked out a small state road on the map. On this state road, the hitchhiking was EASY. I never waited more than 20 minutes, a HUGE differance from the BR! All the rides were short, but they came often. In six hours of hitchhiking I made it about 120 km, six or seven short rides. And the bus took me for free - twice! Anyways, it´s a helluva lot better than wasting your life at a Petrobras on the BR.
Hitchhiking in southern Brazil is actually easy - just stay off the federal roads!
-MN