Yea that's true the brine shrimp they sell as "sea monkeys" probably doesn't have a great hatching rate since they are just for kids to look at really not for being relied on as a fry food. You can find good quality ones on e-bay I saw some 90% hatch rates awhile ago. But they get more and more expensive it seems as the hatch rate increases and the amount you want increases. Sometimes pet stores will special order the big cans depending on the chain. Mine said they would...but it would be like a big 50 dollar can lol I don't need that much yet. So I said n/m for now.
PS if you are interested in microworms for fry as well I just ordered some starter cultures off e-bay very very cheap! You could go with those as well