We reached out to the manufacturer of the Turf Blue HGT with Yellow Jacket seed regarding this question and this was their response: 

"We don’t double the seeding rate even though there is half the seed as we’ve done trials that have shown equal or greater turf performance and establishment comparing our yellow jacket seed enhancement to the same seeds without coating. Basically more seeds survive and get off to a better start with the addition of yellow jacket so it takes less seed to get the same turf coverage. The product performs best in non-ideal conditions, such as home lawns that are under or over irrigated, golf courses and sports fields in sandy soils, or areas that don’t receive any irrigation at all.

The products we want people to be on the lookout for are those with coatings that don’t provide any benefit to the seed itself, so it is good to hear customers ask these questions! This seed enhancement contains some fertilizer, superabsorbent, disease protection, and is brightly colored to help avoid seeding skips."

According to the manufacturer of HGT Kentucky Bluegrass Blend with Yellow Jacket , Yellow Jacket is like having a sponge around each and every seed. Once water is applied, the coating holds that moisture and other nutrients around the seed - making them available as needed for germination. Without coating, the water simply passes the seed allowing it to dry out, resulting in more frequent watering and increased expense.