Probably the case. What is there to resell to the type of people who knowingly buy stuff off shoplifters? With rare exceptions such as when they have an alcohol licence I don't think they have anything worth "commercial" level shoplifting.
You mentioned though that you used to work in legacy media of some kind. Out of interest - suppose though that someone was stealing copies of RAIL to flog off to the OPs of Disputes & Prosecutions forum (fun example bear with me). One of my teenage jobs was working in a village shop and something we had to do with the papers/magazines that were unsold was send them back along with the numbers we were sending back. I assume there's a similar procedure now. Question is - does anyone count them? While I manually did I could imagine that WH Smith's automates this based on their EPOS. I could also imagine that whoever takes them back (Menzies distribution in our case) doesn't count them either. So it's possible that in most cases they literally lose nothing at all from shoplifting of magazines/papers right? That burden instead being taken up by the publisher.
Is there anything in my little hypothesis?
I'd guess things may have changed since I worked for them back in 2008 (so I was there when they started their decline from respected retailer into overpriced floggers of tat), but one of my jobs was indeed counting up and sending back newspapers.
They were sold sale or return, and yes, we manually counted each example. Fine when there were one or two, not so fine when there were 80 copies of the Daily Mail left over because it didn't have a pretending-to-be-free-DVD in it that week. So as such, because they weren't returned, any that were shoplifted went to the expense of the store, not the publisher. We had regular reports as to the "unders" - and eventually solved why we were regularly being shoplifted of the Irish Post (or one such ROI newspaper)... it turned out only the guy who did it in the week knew that it came from a different publisher, so the rest of us, shop manager included, were sending it back with the regular stock as "write-ins". No, we never got credited for it by the "wrong" publisher, either! I think they spot-checked, but most of the time what was on the form was what was paid for.
More generally, I'm saddened (as they gave me my first "real" job, as they did my grandmother 50-odd years earlier), but WHS has long lost its shine. As others have commented upthread, it became less focussed, running after the first quick buck rather than attempting to rival Waterstones or other stationery retailers. My branch was reduced in size (they closed upstairs - the DVD/stationery departments - ... how that somehow reduced the rent I don't know, as it was still connected to our equally upstairs storeroom, staffroom and toilets), turned us into a clearance store (which meant we got everybody else's unsold tat) then, thankfully after I left, closed down. We were
the newsagent for the town centre at one point, with a queue outside the door at 10am on a Sunday morning... how they couldn't make that work, I do not know.
The "bounceback" vouchers (x% or y pence off z product on your next visit) were monitored from head office, and again, there was a league table of stores who failed to scan vouchers per customer. Note failed, not "yay, this store scanned 96% of vouchers" but "Boo, this score only scanned 84% of vouchers). Never mind that there were customers who bought their newspapers from us
Every. Single. Day. and didn't need seven of them over the course of the week. A weekday colleague used to scan the voucher and not give it to the customer! (Or ask and say "did you want the voucher"). As the till sales moved on from the occasional bar of chocolate to a mass of junk that made it barely possible for customers to put things down to be scanned, she perfected the art of "Can I interest you in any...." performing a sweeping arm movement over said junk like cabin crew pointing out the emergency exits. She saved about 30 seconds a customer by doing that rather than mentioning each item individually!
We notices a bit of a drop in customers when they first ditched the Clubcard (the replacement scheme never took off, to the extent that the publicity level when that was withdrawn was about 5% of that when Clubcard went), and just over time, people realised they could get the same elsewhere. Would you rather buy your book from Waterstone's smart tables and wooden bookcases, where books are shown off to their best, or WHS' decade-old, chipped, metal shelving with its special layer of ingrained dirt, where books are just rammed on the shelves spine out and hope. If you had to go to HMV (we still had one then) for your DVD, Rymans for your pens, Wilko for wrapping paper and Boots next door for a sandwich and drink that was half the price of ours.... why would you still go to WHS for your book, when you could also buy that in Waterstones?
I'm still a member of the Facebook group for staff past and present, and it doesn't seem like there has been much morale (or store improvement) for years. My old boss escaped a few years ago, and is now a registrar of Births, Deaths and Marriages - even working for the local authority is a better environment than a retail manager, for her.
The High Street business is failing because management made it so.