We always described Santa as "the spirit of giving" to our kids, as well.
The first time I ever heard of this elf on the shelf nonsense was one day when they came home from school a few years back and the teachers all had them up. I shut that down real quick. Explained to them that it was no different than a stuffed animal in their bed and that they were free to tell their teachers that surveillance and blackmail weren't cool and their teachers could reach out if they had an issue with it. Never heard from them.