Lower fee after client becomes a regular?

Rover, Overall the 20% that you guys take is much lower than other services - and you are running a business. I understand. But I am curious if you have ever considered lowering the percentage to say 15% after say the third or fourth time a client books. I understand that you brought the two parties together - and should certainly make a fee for that - but by the time a client has book the third or more time it's certainly to the credit of the Sitter that the relationship continues. Perhaps the feed should go down at that point. It seems fair.