Exactly this, the interstate wasn't built for profit - and the importance of interstates for US economy can't be understated. More recently, China have managed

Exactly this, the interstate wasn't built for profit - and the importance of interstates for US economy can't be understated. More recently, China have managed to build more high speed rail network than the rest of the world, and served it at loss. As I understand and having personally rode it, the effect of such transportation option to both the economy and personal convenience can be said to rival that of the interstate.