US booking agents are supposed to hold the funds until after the hunt. This is why they get a commission. This is the point of using them and not booking direct. No funds, no leverage.
You're mistaken about that as well....... there's no rule that says that and of the many, many outfitters I know in a variety of African countries only very few would accept that stipulation. (Even in Zimbabwe). Of the agents I know, very few would even suggest that to the outfitter. Believe me, most agents that tell you that are not being quite accurate. Hell, in some African countries the client isn't allowed out of the country until some or all of the various Government fees are paid.
The reason agents get the commission is because if they don't get it, they introduce the client to someone who will pay the commission. - Simple as that.
Now lets get back to your experience of Africa, it's hunting and it's hunting industry?