Sure, but insurance companies also routinely pay only part of the cost - I.e. if the hospital has evaluated that a CAT scan costs them $1250 to do, and they need a small profit margin (make up your own numbers), they need to bill the insurance $3300 just to get $1400 paid out. Insurances routinely only cover a certain percentage of the cost (to save $$), so hospitals have to bill more to get the $$ they need.

And I'm not saying the hospital is innocent here, but this "costs more when billed to insurance" is a long-known issue.