I used to work for a regional record chain back in the early 80's (Strawberries Records and Tapes).
Started out in one of the stores then took a position at the warehouse for more hours and money.
The stores had some weird security system for buying cassettes.
They were enclosed in a plastic frame similar to the one posted and were locked behind plexiglass with holes cut out
just large enough you could put your hand through to grab a cassette but not large enough for the cassette to be removed.
The customer had to drop the cassette with security device on a conveyor belt at the bottom of the displays and it would be
transported to the cashier.
Remember the Ban the Box campaign?
https://shortformernie.medium.com/compact-disc-longbox-history-4e5b91f7564CD's had just came out when I was at the warehouse and unlike the albums and cassette tapes, they were locked up in a cage that only a few people had access to.
Initially there were only a few artists/bands available. Predictable stuff like 'Dark Side of The Moon', 'Thriller', 'Sgt. Peppers', 'Led Zeppelin IV, etc and they
weren't cheap. From my foggy recollection something like $20.00 in 81.