Too many folks spouting too many figures and facts(?) make this too confusing.
I'm not really familiar with the LAWs, regulations and common practices all over the country and I don't care to be. I follow what has been successful for me for my lifetime. I prefer to have my five gallon cylinders filled at a real propane dealers depot. Our local dealer will fill it however you want, by using the spit valve or by using the scale. I'll be honest, I don't remember if they use the spit valve on the Winnie's tank or not.
I always walk with the guy who filled my cylinders or tank back to the office to pay and I noticed that there are several DOT and CalOSHA certificates of training on the wall.
They have been in their current location for decades and I've never heard of an explosion at their depot. It is my practice to get my propane at recognized propane dealers, not at a market or big box store or at a gas station. I don't go to CVA for medical advice, I go to my Doctor, same idea.