The first "Flashing Rear End Device" use is attributed to the Florida East Coast Railway. Following an acrimonious labor / management struggle - which began on January 23, 1963 and ended on April 9, 1976 - the Florida East Coast was the first railroad to eliminate the caboose, forcing the conductor to move to the head end and eliminating the fireman and two brakemen. And created a need for a device to monitor air brake pressure!
The latest generation of EOT's incorporate a turbine, driven by brake line pressure, to operate the flashing red light, and keep the internal battery charged.
Unfortunately, there is an entire generation who have never enjoyed the pleasure of waving at the train men passing in the caboose, (crew car, hack, way car or crummy) believing that FRED is the end of the train.
I've said it before, and I'll say it again. "A freight train without a caboose is like a sentence without a period "