Yeah, you're a fucking island. The rest of us should just fuck off and leave you alone.
The airline submits this information to Secure Flight, which uses it to perform watch list matching. This serves to prevent individuals on the No Fly List from boarding an aircraft and to identify individuals on the Selectee List for enhanced screening. After matching passenger information against government watch lists, Secure Flight transmits the matching results back to airlines so they can issue passenger boarding passes.
In other words, YOU are required to tell the government you plan to travel, and they get to decide, in advance, whether you can. Assuming you're not, in their own words, on any "government watch lists".
You can read all about the Intelligence Reform and Terrorism Prevention Act of 2004.
The first version always gets thrown away.