I said for pickup sized trucks....We really don't use very much.
And I would be shocked if the big rigs do not have some sort of filtration system built in. Obviously if a system is much larger, and designed to handle contaminants that may find their way into a tank, then the cost savings of purchasing in volume vs. the smaller risk because of a protected system may well make sense.
Just do the math, even at the inflated figures that were given here... How much will you save over the life of the truck? How much will one visit to the shop cost to fix it if it is a problem?