[rrrix1]

For desktop, server, web, mobile, etc. This holds true. Not so much for embedded systems, anything with unnatractive memory capacity or processor performance. Rust is starting to make it's way in, but C and even assembly is still king AFAIK.

[pizlonator]

And yet there are embedded systems running JavaScript and Python.

[kv85s]

Are there any real-world, production systems based on JavaScript and Python?

Toy systems, yes. Hey, I too, think CircuitPython is really neat. But I'm skeptical someone would base a PLC (or similar) on it.