Not a legal expert, but I assume a couple of things are true:

1) It has to be a business land, not your backyard for the tax status trick to work. I don't think you can just bury grandma in your backyard and claim your house is now a cemetary and you get a tax break. You can bury her there if you want, but if you're hoping for an economic reward from it, it's not coming.

2) Most people who own a business don't do this on their business' land because most people would find it disrespectful to the person they're burying there. Trump is not most people.