My guess- there's not enough money in it. If there was significant money to be made, others would be there. As it is, there are other options. Fan manufacturers make "smart kits", you can buy a "smart" fan controller switch (both require you to do some wiring) or you can just buy a smart ceiling fan to replace your current one. If spending more money is your concern, don't try automating your house. It's not an inexpensive hobby.