I can’t see reddit on my network(I blocked it to avoid using it) so I will take your word for it, I’m assuming its the store freezer/produce doors with ads.

Being said, there are reasons to technologicalize the process. those type of low level mini pc’s or controllers last generally years at a time, and are a setup once and done type operation. They are also super cheap and can be distributed across the entire chain once instead of needing to get material, print it, and ship it every time a new product or design is done. Sending stuff over the wire is cheap, shipping marketing material is not. It’s generally sent from a different company all-together, and either centralized into a distribution center to be shipped to the stores, or shipped directly to the store from the producer.

It also allows for video based distribution which allows for more info on the screen (for better or for worse because this also could be ads).

I think it’s dumb that it’s an individual system it seems for every screen, but I expect that HDMI matrix hardware is more expensive vs just having them separate, but regardless cost wise it’s a no brainer to make it digital over having physical inserts, even if its more wasteful.