This is just not true as a blanket statement. I am as cutting-edge tech-wise as anybody (it is my industry, after all), but that doesn't blind me to the fact that there do, in fact, exist use cases for which the fax is the best solution.
Legally, this is interesting because it doesn't exist in email. You had the machines agree that the complete document was sent and was received. You will certainly find that it other transfer protocols, but not email, where the machines don't talk to each other directly.
Also, even when you have both an internet connection and a camera, there remain numerous possible reasons why you may not want to use the internet to send certain things.
I'm certainly not saying that everyone should start faxing, but I totally understand why there may be a substantial minority for whom it makes sense at least from time to time.