Just like a manager, you don't need to look at the code. You need to set up quality systems to provide evidence the code does what it is supposed to do, just like a manager.
Code review has a number of important purposes beyond merely verifying functionality. It's true that some managers don't recognize this, fail to allocate time for anything but feature work, and then wonder a few years later why the software is so buggy and new feature development is so hard.
I’ve never met a manager that have setup “quality” systems to ensure that the job is done correctly. Their actions are always retroactive. And not pertaining to code at all. The overarching contract is “You do a bad job, you will be fired”.