The Cakes are bakers
The Apples are apple farmers.
The Riches have riches.
So, it isn't strange the the Grims get all the dark, dank, bloody, nightmare giving jobs in Equestria. I mean our ancestor is Nightmare Moon so I guess what else is expected. We are a family of undertakers, assassins, torturers, miners, hunters, warriors, and thieves and our family couldn't be stronger. We are a band of outcasts and nopony will ever change that. Well except Celestia.