I keep having to tell myself it's not rude

This is how you get someone's attention in Brazil:

Make some kind of noise. Any noise. It can be a cat call, a whistle, an "oi!", a "hey!", a cough, a yell, or whatever else you want it to be. Once you get their attention just by the sheer fact that you made noise on the street or in the room, you just talk to them like normal.

Never mind the fact that you just made everyone else look at you too. It doesn't matter at all. Just ignore everyone else, it's their problem that they have ears.