Comment by Animats

The whole point of the Magic Eye tube was that it was cheaper than an analog meter. So it was the consumer-grade replacement for one. On pro gear, you'd find a meter movement and pointer, which is harder to make than a vacuum tube.

In "The Day the Earth Stood Still" (1951, not the remake), when the visitor goes into his flying saucer and powers up a communicator to report to HQ, there are two huge Magic Eye tube like devices. So back then it was a cliche for "radio". Start at 55 minutes.

[1] https://archive.org/details/day-the-earth-stood-still-1951