I'm in CA, where it's about as strict as I've seen or heard about, having lived all over both costs.
Here I've seen it pretty common for alarm installers to find a reliable outlet to plug the transformer into, then fish the wire right from the transformer into the wall, up into the attic, and back to the panel - wherever it is. It's LV so CA doesn't care much. FWIW.
Also a new practice that's very common, and VERY against code - is all these flat-panel TV installation kits - that give people a wire passthrough from behind their TV to a hidden location... people are running their standard TV AC cords through these wall cavities, which is explicitly against code - but it's happening every day here, and nobody is complaining.