I feel the same way!!
Here is how I wrote Fiverr with my concern:
Apr 14, 10:15 AM EDT
I’m TOTALLY on-board for the 20% Fiverr takes out of my earnings, since Fiverr gives me a huge exposure without I having to do a single thing, also since the site makes possible smooth transactions, with them acting as escrow services…well, you get my meaning. But I DO NOT understand WHY Fiverr takes a 20% from my TIPS!!! Tips have NOTHING to do with the mechanics of the site nor with the way information is presented, or how smooth the transactions are made…it is a GIFT clients decide to bestow upon US the sellers because of the way we treat them, the level of sacrifice we are willing to take to bring their projects to fruition and the things we have to endure to guarantee that process…I belive your policy of putting your “hand” in my private “cookie jar” is a very despicably GREEDY practice that denotes a very warped sense of ethics and knowledge of proper business etiquette!!! Hopefully this point will be brought to a future Fiverr discussion and you will have the opportunity to change this to a process more in-tune with the image Fiverr wishes to create AND maintain in the internet world!!!"
Hopefully I’ll get a reply!