I don't suppose we have an easy way to see how much money they receive.Do we even have a way of knowing how much money they receive? How do we know they won't keep some?
As for how do we know they won't keep some, they are one of the most trustworthy anime stores in existence that has been around since the early days of anime and if they got caught trying to skim money from something like this it would destroy them?
If you don't want to trust them that's totally fair, but I personally have no issues trusting a company that has been one of the best for anime to get 100% of my money to the people that need it instead of giving into fear and only having like 80% of it making it there.