In particular, Dr. Richard Hipp (SQLite's main author) has talked about problems that came up from releasing it into the public domain. He eventually created a second license specifically for companies in places that didn't legally recognize the public domain, and wanted to make sure they were protected from liability.
CC0 addresses these problems with "public domain"; its intent is the most permissive license that's legally possible (plus, in jurisdictions where it is possible, actually placing the work in the public domain). Unlike the other Creative Commons licenses, it it suitable for source code.
In particular, Dr. Richard Hipp (SQLite's main author) has talked about problems that came up from releasing it into the public domain. He eventually created a second license specifically for companies in places that didn't legally recognize the public domain, and wanted to make sure they were protected from liability.
Licensing is complicated.