Nick, even if the health department allowed the use of raw milk, I can't imagine the nightmare of trying to keep enough dairy cows to meet our requirements in the small space we have. Have you ever been to a dairy farm? They stink.
As far as pouring onto a scale goes, yes, that would do the trick. But what if you could do away with the opening the cooler, removing the milk, removing the lid, taring the pitcher, pouring very slowly to hit a +/-3g target, pouring the extra 5g back into the gallon, putting the lid back on the milk, replacing it in the cooler part?
I realize switching bags would be a pain, but if you only had to do it every 5 gallons, that wouldn't be so bad. Also, my dairy gives a nice price break for the 5 gallon bags.
Remember back when timed grinders came out and people thought they took away from the artistry of making drinks?
...aaannndd the Starbucks down the street just got a Clover