How much material can I haul in my pick up truck?
Well, that depends on what you're hauling. If you're hauling mulch in a full sized pick up with a full sized bed, you can fit 2 cubic yards in the bed and have it be level. While 3 yards is a heaped load. If you're hauling soil, weight then becomes the issue. Most pick up trucks can hold 2-3 ton/ cubic yards of topsoil, however they can only haul 1 ton/ cubic yard.
Why weight to determine accuracy?
Weight is unquestionable while volume can be subjective. Why? The certified scales reduce the human error factor. In addition, operator techniques vary causing variance in the compaction of the material in the bucket.
What if it rains the night before? Am I paying for water?
NO... Weights are taken at the beginning of each day and up dated according to changing weather conditions throughout the day.