Issue with billing account user

The demo for billing account user shows that any user can create his own project and attach it to billing account, and the admin can’t see the project as it’s owned by the user who created it. But what if the user uses like a $1000 bill on his own projects and gets away from the company? Admins can’t even track this expense, correct?

So as far I understand, the project creator and billing account user should not be given at the same time unless there is a restriction that billing account user can only add existing project under that org only, correct?

Please clarify, thanks!