Former land surveyor and GPS/GIS technician here (now a developer). I have a lot of sympathy for your perspective. I remember when consumer GPS became a thing and getting a little Sheldon Cooper on folks who used "GPS" as a synonym for consumer-grade hardware: "don't you mean GPS navigation?"
But that train left the station a long time ago, and I've stopped arguing with people about it because it's a losing battle. Every normal I know, from my parents to my network of friends, refers to Garmin and TomTom auto units as "GPS." They have unfortunately become identified in the common mind with the technology.
That does not mean one can't protest it ;). You need a way to refer to an actual lousy GPS as well (long fix time, inaccurate). Lumping everything together makes it hard to be precise (like using 'begging the question' wrongly somewhere else in these comments ;)).
I don't like it when words I know lose power either, but language changes under stress of modern usage and wrong becomes the new correct. 'Literal' became the new figurative. And so it goes.
But that train left the station a long time ago, and I've stopped arguing with people about it because it's a losing battle. Every normal I know, from my parents to my network of friends, refers to Garmin and TomTom auto units as "GPS." They have unfortunately become identified in the common mind with the technology.