That is true. We run into clearance problems a lot because of our customers trying to put 10 pounds of something in a 5 pound bag.
Here in our facility (the Island of Misfit Toys), clearance is a constant battle. I've been down this road so many times, it become acceptable in the current age of technology that "clearance", to those who punch computer keys and come up with floor plans, includes just enough space to get your cell phone into to take a picture of the fuse sizes, 'cause you sure ain't getting your hands and head in there.
As the statute is written, I take it mean anything that needs to be accessible for service, whether that service is pulling wire, checking voltage, changing fuses, repairing a latch, etc. If it has a cover and there's a possibility one would need to EVER access the innards, it should have 3' (in a perfect world). Personally, I very seldom get access to that luxury because people who draw never have to work inside the hell they've created.