Judging from this news article[1], it seems like there aren't many warehouse workers that 1) work there full-time, 2) have worked for 3 years, and 3) have the free time to pursue a degree.

Then again, the money may be targeted towards warehouse managers, who Amazon could see as potential higher-ups in the main organization if they had formal training.

[1] http://www.motherjones.com/politics/2012/02/mac-mcclelland-f...