Amazon doesn't have the... 'Washington Infrastructure' to be able to compete at a regulatory level, so they have to compete on price like any other homeless vagabond.
For PACs in the 2012 cycle Amazons PAC spent $220K, Microsoft spent $2.3M, Oracle $540. In direct lobbying this year Amazon spent $1.7M, Microsoft $5.5M, and Oracle $3.7M.
So yeah, Amazon is paying to get representation. But they're still significantly smaller than the "enterprise" folks.