So if you get 150 lbs. of Golden Shiners, or 150 lbs. of fatheads, do you hand sort that? I think not.
Dealing with the supply of live things has to have flexibility.
If you are buying a few pounds or gallons, then I think you can hand sort if you like.
But as far as the expectation that you didn't get your money's worth if you ordered a few thousand fatheads and got a rogue sunfish in there, I can't buy into that. Actually, nobody 'bought' into it. Not enough money was paid to have the kind of guarantee, in my opinion.
I do understand the desire to do everything you can to get exactly what you want. I also understand the importance of this when running very, very goal-specific projects such as maximizing bluegill or YP growth as members do. But I also think those are done in smaller ponds where you might only order a few pounds of a species. Then you can hand-sort. But for a fish vendor to have to certify that his fish are 100% what you bought for say $10 a pound, I don't see the validity of assumption.