The 0.20% is the avg rate that exchanges charge.
What the exchange charges is not the service provided. The service provided is
1) Selling at survivable exchanges
2) which one wants to be the most profitable exchanges,
3) large amounts,
4) while the coins are being or about to be dumped by other multipoolers, and then
5) redistributing the proceeds.
I do not envy the task of autoexchange for a multipool.