Keeping it simple is great as long as it doesn't get too complicated. The road to Hell is paved with good intentions, and we're on our way. Let me back up a little. Washracks have separators that supposedly allow only water to run off into the drains. The fact that the only washrack on the entire south ramp at HNL has a perennially-clogged drain is immaterial.
Similar problems exist at other state airports.
Recently, a person was taken to task for rinsing off a glider at Dillingham. That's just silly. Fact is, salt is highly corrosive and the only way to try to keep an aircraft airworthy is to wash it frequently. Of course, when it rains, my Seneca gets wet and the rain runs off, just like it does off every other aircraft parked outside at any airport in the state. Rather than come out with a sensible requirement for using biodegradable, environmentally-friendly detergents, the simpler course was to just ban the practice.