300MB; 3GB; 5GB; AT&T; Unlimited on Sprint?!

AT&T currently only offers 5GB as the highest they can go for data on smartphones, 300MB for lowest. I think the days of unlimited are gone if you want the highest owned smart phone in the us. The iPhone however, I hear sprint has the new iPhone 4s. It is important to note, that sprint still offers unlimited Data. Everyone is sitting here scrounging around to save data when at work, school, on the bus, or in a long long boring wait. Now if Sprint can offer data at unlimited plans why can't every other carrier? Chew on that iPhone owners and the likes.