Here in New Hampshire it is unlawful to have a cocked crossbow in a vehicle even without an arrow on it.
Honestly, If you have hunted with a crossbow, then you know it is a pain to haul a crossbow target to shoot/unload your crossbow, Worse yet to keep a heavy and costly bolt to shoot into ground to unload it. My Excalibur Grizzly can be safely de-cocked with rope but loading it multiple times is not great for my back. Now manufacturers are creating user friendly cranking bows with de-cock capability like the Fury 410 DECOCK.
I have not shot one but have asked Wicked Ridge to send one to test for our readers.