Who coordinates subcontractors working in the same space?

Short answer. You do, as prime contractor. A typical rough-in sequence is plumbing first, because of pipe pitch, then HVAC ducts, then electrical, which routes most flexibly. Set the schedule before anyone arrives.

Work it through

You're the contractor. Pick what you'd do, then see how each choice plays out.

You have three subcontractors on site simultaneously: framing crew, plumber, and electrician. The plumber and electrician are arguing about who runs their lines first through a shared chase.

Both claim the other should work around them.

Correct
As the prime contractor, project coordination is YOUR responsibility. The typical rough-in sequence in shared spaces: plumbing first (rigid pipes, gravity-dependent pitch), HVAC second (large ducts, hard to reroute), electrical last (most flexible routing). Setting expectations upfront prevents site conflicts. If you're not coordinating your subs, you're not doing your job as general contractor.
Weak leadership
'Figure it out yourselves' leads to wasted time, redone work, and angry subcontractors who don't want to work with you again. Good subcontractors expect the general contractor to set the sequence and coordinate access. Failing to manage your job site costs money (idle crews waiting), quality (rushed work to 'get out of the way'), and your professional reputation.

Who coordinates subcontractors working in the same space?

Work it through

All 14 subcontractors, liens & workers questions