Like why doesn't `println` in a modern language like rust auto-escape output to a terminal, and require a special `TerminalStr` to output a raw string.
Consider cat. It's short for concatenate. It concatenates the files based to it as arguments and writes them to stdout, that may or may not be redirected to a file. If it didn't pass along terminal escapes, it would fail at its job of accurate concatenation.
Now I don't mean to dismiss your idea, I do think you are on the right track. The question is just how to do this cleanly given the very entrenched assumptions that lead us where we are.
This is usually knowable.
It's a different question whether cat should be doing that, though – it's an extremely low level tool. What's wrong with `less`? (Other than the fact that some Docker images seem to not include it, which is pretty annoying and raises the question as to whether `docker exec` should be filtering escape sequences...)
The C0 control set (ASCII 0x00 to 0x1F) contains all sorts of esoteric functions, most of which are generally unused, and only a few of which are useful and could be implemented at a higher-level. ESC sequences are only part of the problem.
And this also applies not just to terminals, but to systems programming as well. None of these have any business in e.g. filenames, but it's all commonly permitted. Some systems do forbid them, and it should IMO be universal.
If we really want to fix this, then we would develop a character encoding that strips out all control characters entirely, including LF and CR, and have text be nothing but graphic text characters. It's so entrenched and convenient that it's difficult to see that happening. But I do think routine stripping of all control characters in situations that don't require them would be good for security.