Why would it not be the case? The important thing to report to investors is the financials. The last thing you want to do as a company is advertise to your competitors exactly which of your products are failing and which are succeeding. Also, it would be insane if companies had to report "Unit sales" do they have to report iPhone 7/8/9/X? Or 7/8/9/X + different colours? How about X vs X+? Do you need to know iPhone X+ White 64GB sales?