If it ever will be 🙁 So you really shouldn’t design systems that assume it is.
A couple of examples…
The bank I use for my business recently “improved security” for setting up transactions over the internet so that any new payees or changes in payment amounts and references (and a few other account details changes too) require a confirmation code to be entered. The confirmation code is sent to your phone as a text message. But mobile network coverage from our home and my office is so poor that I don’t get text messages, meaning I can no longer make payments using internet banking. I have to phone them up to set up the payments instead which takes considerably longer and means I can’t cut’n’paste details from emails or electronic invoices.
And today we were visited by a chap from the AA who is working for Volkswagen, updating the EMU firmware for their cars, presumably as a result of the emission-fixing scandal. He got out of his van holding his phone, saying “I can’t get any network coverage”.
“No”, I replied, “you won’t.”
“Oh. We’ll I can’t do the software update without mobile phone access.”
Fortunately he managed to do it a different way once I’d allowed his phone to connect to our wifi network, but that was only possible because I have a wifi network deliberately set up to provide access outdoors.