I'd guess that Bia is right and that it has more to do with styles of teaching and studios than anything else. Where I come from the only option is International Standard and Latin and Standard is what's danced socially. If you're going to be any good as a social dancer you've got to know how to follow. Lead and follow was the main focus of my lessons from when I first started to learn to dance. I remember my teacher saying to the leads that a good lead will lead the follow through a step they've never done before and to the follows that if you're responding properly to the lead you can dance anything. I don't think that everyone is taught this and I don't think that everyone gets it, though. I well remember dancing with a man who commented to me, "Gosh, you really do follow don't you!". He was used to ladies dancing set patterns regardless of what he was trying to lead.