14gauge on commmercial for power supply is one of those things that is just never seen, but it's not because of a code restriction.
In alot of places, including the northeastern Ohio area that I'm in, residential projects don't have electrical prints. Residential project are inspected to code only.
Commercial projects are different in that they must have prints. Those prints must be approved by an architect or engineer (and the AHJ plan reviewer) and apparently they are taught not to include 14gauge conductors for power distribution.
Commercial (and industrial) projects have 2 minimum requirements enforced by the inspector, code and prints. We require to installation to follow everything on the prints. It doesn't matter if we think it's important. The architect or engineer stamped it. That's the way it has to be installed.
David