U.S. Unveils $53 Billion High-Speed Rail Plan

I'm not American, but travel to the US regularly, and think it would be great for the US to have high-speed rail. I've recently travelled on AmTrack a few times and it is a very good service.

The question I'm wondering is, if Warren Buffet has seen the enormous value in the future of the US railroad, why is this plan being brought forward by the government, rather than a public/private partnership?