JavaScript and Python need to calculate filesysizes, measure network bandwidth and track memory usage just like every one else. There's also of course bit shift operations and byte arrays. Heck byte size is relevant to floating point even.

Two things:

As the saying goes: if all you have is a hammer, every problem resembles a nail. You can validly say "I've never actually needed a screwdriver", even if the screwdriver might have been more useful for the job at hand.

It also depends on what domain you're working in. I just happen to have been working on a Python/JS GUI to operate a Robot this past month. Interfacing with the Robot did require use of bits and bytes. Fortunately both Python and Javascript do support those operations for just those kinds of situations.

So while I do agree that some jobs can be done in javascript and python where you can avoid needing bits and bytes, that's my two answers:

1) Bits and bytes sure can come in handy at times. They might be the best tool for some jobs.

    and

2) For some jobs you really do need to manipulate bits and bytes. You can't avoid them forever.

So if you like writing a lot of different kinds of programs for a lot of different kinds of things, you're almost certain to end up using bits and bytes sooner or later. Do that often enough and it does tend to stick. That includes Python and Javascript.