What I'm saying is that developers typically don't have their own hierarchy. Sometimes there is a "lead developer", but usually there is a non technical person over top a group of developers, and that person is given an office and more respect.

It has been shown time and again that open floor plans actually harm developer productivity more than they help it. Imo the most reasonable mid ground is giving developers larger cubes big enough to allow pair programming when desired. High cube walls are necessary also so that conversations within a cube don't make it impossible for nearby desks to concentrate.

Janitors and security guards aren't usually employed by the company, are they?

What makes you think from an organizational perspective that there is a difference between them? It is far more likely that the engineers are viewed as having similar fungibility as the janitors than management is viewed as having similar fungibility (for example).