They also sometimes own the machines in the field closets. So, anyone can rent 1U + a bunch of fiber endpoints for the same price. What you do with the slots

They also sometimes own the machines in the field closets. So, anyone can rent 1U + a bunch of fiber endpoints for the same price. What you do with the slots is up to you. If there's a problem with the power or actual fiber optics, the common carrier fixes it. (Like a colo, sort of.)