None of those are actually that rarely sold.
I do wonder how often SILK procedure is used these days. From various chats with some ticket office staff, not very much (if at all at most stations).
Had one just last week...which was "fun" because we had trouble finding a phone number for the other station thanks to the lack of railway switchboard, and the number in Knowledgebase not working! Ended up going via the other TOC's Control.
As for AAA tickets, I've sold
one in my career, and that was down to a student extracting the urine with the amount of luggage they were carrying (and monopolising a mobility assistance buggy to get to the train!). If memory serves, there was that much luggage that the AAA charge worked out to more than the ticket price.
Similarly, I've seen precisely one Travel Agent Discount Authority, though the agency hadn't ticketed it for some reason so we duly sold the required ticket.
I've never sold a Dutchflyer (Harwich - Hook of Holland) ticket, but I
have sold several Rail-Sea-Rail tickets to Irish destinations.