Blonder tongue was a well known vendor for regional cable tv network (analog) operator equipment, supplies, electronics. I think it still exists in some form for video mixing/live studio broadcast equipment.
I work in a lot of nursing homes and their in-house "cable" systems are almost universally a rack full of DirecTV receivers connected to a rack full of Blonder Tongue NTSC modulators. I would have to assume similar systems were common in all sorts hospitality environments in the past, and only survive in nursing homes because most of the residents don't care about HD and might not even want it.
The is probably how all jails and prisons are running their systems, too. Lots of these places still running CRT 4:3 TVs too. The 4:3/16:9 issues are rampant. And obviously the picture quality is just like you remember from the 1980s.
On a only slightly related note, there's a thriving collectors market on ebay and other places for "clear plastic" see through enclosure prison CRT TVs since they're both a novelty, and nobody makes CRTs anymore. People buy them to hook up to like Sega Genesis, Super Nintendo bare metal hardware for retro gaming.
It's getting harder and harder to bring them home. The prisons are trying to keep the items inside the system, even though the prisoners actually bought the items outright.
https://www.blondertongue.com/