Depending on exactly which scanning program I use, I've found that scanning the same document with the same settings (e.g., letter size [8.5" x 11"], 300 dpi, black-and-white) can produce PDFs varying in size by a factor of *50*!
And every Internet site has different rules on what uploaded file sizes and types are acceptable, and they require countless usernames and passwords to juggle, each with different rules on acceptable usernames and passwords.
I waste hours, and hours, and hours, and hours on such crap.
It is so much easier, slow as it is, to print, sign, and snail-mail documents to recipients, when they can still be bothered to accept them that way.
Actual POTS 14400 bps faxes, while that got me through college and trading technical documents and papers and problems, and it was cool in the 1990s, I don't miss at all. 2 words: thermal (printer) paper.