This is in the Fantasy genre because its robot friends, ghostly helpers, and unearthly census takers remind me of Scarecrow, Tin-Man, et al in the Oz series. Before humans made Earth damn near inhabitable with super-weapons, they left the scene of the crime for other planets scattered about the galaxy. But the company called Cemetery played the heartstrings of the migrants and sold them burial plots back on the Earth. By the time 10 centuries have gone by, the company has turned vast tracts of land into boneyards, developed rotten ingenious scams, and pushed the remnants of human bands out of the way with carrots like alcohol and sticks like robot wolves. Two humans (the starving artist boy and social scientist girl) from the gentle planet Alden visit Earth to make art and find a treasure. Simak captures the cheesy classical artificiality of North American cemeteries. The descriptions of nature in autumn will make anybody from Ontario, Michigan, Wisconsin or Minnesota sigh.
I'm sure this is a great book, if you like science fiction fantasy, which I do not, so I didn't get into it at all.