For what it's worth, I run into the same nuances frequently in Python. For example I often want to run

    some_script.py | tee log.txt

But by default, Python will turn off line buffering when it detects it's not talking to a tty. So unless you know to call flush, or to add the right env var or interpreter flag, you're not going to see any early output from tee. This can be super confusing for newer programmers.