In the same question, this answer hasn't attracted a banner about references being needed, and yet this version of an answer received a banner about references. (This answer currently also has received a references required banner, but I haven't looked at that answer closely)
In the answer that didn't receive the banner, I explained in the comments (since mostly moved to chat by mods) my concerns about the answer, and got nothing but abuse (1 2 3 4 5 6 7) from the answerer in reply, with no attempt to improve the answer. The mods seem sympathetic to my concerns (1 2) but haven't added a references banner.
Can someone explain when the references banner applies, and when it does not apply? Are the criteria for it being used arbitrary?