No system exists outside of a handful of buildings downtown, so everyone else who qualifies will either need to add in the cost, passing it along, when building a property, or when retrofitting a building, and still passing those costs along. If you really ran a business, you'd know that's how it works.

Soil will dry out faster if it's shallow compared to deep soil. More water usage when water is a scarce resource. You can't deny that.

One of the buildings downtown that I'm aware of, with a green roof, has had some problems with water retention. You claim it won't happen. Believe what you want, but don't expect agreement.