I doubt that 130 miles of copper is the public Internet. It’s presumably some legacy telecom system that depends on a bunch of generally fairly well made but thoroughly obsolete hardware.
Keep in mind that Ethernet over copper is only specified to ~100 meters. Long distance copper networks have been obsolete for a few decades.
Here in my EU state, air traffic control still used leased copper twisted pair for server link over ~150km as of at least 2015 or so. It's pretty reliable and not "public internet" at all - just two modems with known performance and known latency taking to each other.
Might be something like that in this case as well.
Sure, this kind of technology works fine. Except that it might be difficult to find people who how maintain or repair the fancy (pressurized? oil-filled?) copper cables or the modems, and finding parts might be interesting.
I did some enterprise network work ~20 years ago, including fiddling with some inter-building links, rummaging through closets, and visiting the inside of a legacy campus-scale analog phone exchange, and I’ve never even seen the kind of equipment that can send data at an appreciable speed (even by 1990s standards, and even with repeaters) over copper at a range like 100km.
In contrast, single-mode fiber has improved over time, but it’s not obsolete, and it has maintained a remarkable degree of compatibility over the years. New transceivers largely work on old fiber, old transceivers work on new fiber, etc.
It’s called a dry loop. It might be real with repeaters at the various COs, or it might be partially virtualized and sent over a fiber trunk. Usually somebody leading a dry loop does so for the relatively extreme reliability, even though the speed is not very high.
Keep in mind that Ethernet over copper is only specified to ~100 meters. Long distance copper networks have been obsolete for a few decades.