"Today, online magazine quite often present code samples - but I struggle to image that anyone would have typed in all this machine code. Let alone done so correctly!"
That would have been one of the longer listings to type in, but I probably did similar, back in the day.
One of the nice things about the YS hex loader and associated listings is that it included a checksum (the part after the =) on every line. So if you made a mistake, you'd know about it quickly enough.