My D got one last year unexpectedly. I believe it was after an online session or meeting with a rep at a college fair and signing up for more information. We were never sure why she got it. So I know it happens, but I’m not sure what initiates it!
Perhaps others can add more specifics. Or would it hurt to contact Admissions and request one? With some schools it is as simple as confirming you will apply for financial aid and they will provide a waiver.
ETA: I just saw @tsbna44 post. I guess we got it because of applying for the Johnson. Mystery solved. 
Hmm… I’m rethinking this. Wouldn’t we have received the waiver before applying for the Johnson??? So I’m not sure about the mystery being solved now.