Well, duh. Point is, they don't use "complicated instruments" as
claimed by someone else.

I have eight tanks at two houses, three at one house, and two at a cabin.
Sometimes I have taken up to eight of them in to be filled. Sometimes on
the rentals, I will pull a tank when it's low so it doesn't run out while
the guest is there and I'm out of town. When you get eight tanks filled,
how does one keep track of how much has gone into each? And how does the
geek know if he is filling to the suggested 80-85%?

On one tank fills, it's pretty easy to get it close. After that, going
through eight tanks, and using up to 35 gallons, I think the only way to
properly fill is by weight. The rolling numbers will tell the eventual
grand total, but only weight will tell you how much is in a partial that
you're adding to. PLUS, sometimes if they're flat empty some suppliers will
refuse to fill unless they perform an additional purge. (translates $)

So, although filling tanks isn't up to rocket trajectory mathematics, it is
not really simple. Well, it really is, but most of today's idiots don't
have a clue. And I hate to stand there and wonder if this guy is
overfilling or even knows what he's doing. Yes, they do have the overflow
screw to tell them, but do you like to be standing out there with all that
gas around, and a couple of tons more in the tank? I don't.

Whatever winds yer clock. I actually prefer fillers who have "complicated
equipment". Their help is better than some pimply little girl who's had
fifteen minutes training and a ten minute attention span.

Steve