To make chain analysis harder?

Imagine that you are monitoring an address that has 1 BTC. If the owner sends 1 BTC to Bitcoin-Laundry, you know that the output will be 1 BTC (the arriving amount) - 1% - 0.00008BTC, because every transaction from Bitcoin-Laundry has the same config. That's simple as heck to find when analysing the blockchain. Just find a 0.98992BTC transaction made right after the owner moved his coins and you will have the new address. The mixer won't do literally anything to the user's privacy (literally 0 protection).

But now, if you set a delay and customs fees, the user analyzing the transactions will have to find a transaction that is 0.3% to 4% smaller than the arriving one, with a tx fee from 0.00001BTC to 0.0003BTC and being sent from 1 hour to 24 hours after the input. Way more difficult and efficient.