Yeah. Especially on commercials where the water usage compared to a standard resi is so much more exponential .. Rain sensors should be required
The other year our water district alliance groups streamlined the rebate process where the rebate process credited the contractor company instead of the consumer. It's easy to tell someone ' Hey you can have this for free and not have to do anything about it to make sure its free' Since then we have probably installed over 2500-3000 rain sensors.
This also came at a cost of confusion to customers and phone calls to us when there system wasn't working when the rain sensor was just activated.