[agemame]

Fair points and I think I should have clarified my post with the words "in the U.K." somewhere.  As you rightly point out, they're still in-use elsewhere in Europe and Switzerland is one of the bigger areas.  As noted, the primary use is for decryption, which in the U.K. takes place within the STB.  I wouldn't say the U.K. is an outlier in this respect however, as Canada also has decryption in the STB. Certainly the operator I have - (StarChoice  > Shaw Direct > Rogers) used to used smart-cards in the box (but no CAM), but they stopped doing this a long time ago.

And, as noted, On / ITV Digital did issue CAMs, but I'm not sure they were ever particularly popular or well-used, and certainly not really 'pushed' as an option, I suspect as a lot of the TV hardware then didn't have the option to use them, especially as there were still a fair amount of 4:3 CRTs in-use (I used On / ITV Digital with the telly in a spare bedroom, which was a lovely Sony 14" Trinitron ).

The U.S. is somewhat different as cable operators were required to issue, for a time, both their own 'operator-issued' CableCARDs, but also CableCARDs which would allow consumers to view programming on devices other than the 'operator-supplied' STB (such as PC's).  This was meant to foster competition in the STB market, but this never really took-off. The need for operators to support CableCARDs ended in 2020.  Operators wanted to move away from physical security cards and, by that point, streaming was becoming a much larger piece of the puzzle.

N.B.: Incidentally, if anyone wants to see a fascinating documentary on the development of U.S. cable television, I recommend the following:

youtu.be 

I think in terms of being hard-to-understand; no you are correct in that they're not so much hard-to-understand as I think people just won't understand the reason behind them.  Most people will never have come across one, even in Europe or the U.S.  Of course, if it was the only way to get Freely (see how I got back on-point there ) then people would soon pick-up the idea, but there's also quite a few secondary TV's that might not have the ability to use a CAM.

EDITED: 19/12/2023 - 21:56

I believe that when Freeview came out of the ashes of On/ITV Digital there was a significant pushback towards putting the CAM technology into their first run of boxes. Cost was a factor, obviously, but the BBC in particular were keen to keep as much of a barrier towards subscription services sneaking back in as possible. By that same logic, it's hard to see this being implemented as a CAM module, when USB dongles are more likely to be accessible in that specific case.