What about people who are old and not computer savvy, or simply don't have access to a computer and printer whilst on holiday?
How did they book in the first place ?
Given 99%+ plus actually book on line then it kind of gets puzzling how if they could safely book online then how come its hard to check in. Remember the oft published Daily Mail ones are NOT about people who COULDN'T check in there are about people who DIDN'T. Really big difference.
I have probably not travelled as much as you Cape but I do know that I have never struggled to find an internet cafe or a hotel willing to help out even when in Japan in the boonies I spoke no Japanese but did enough to get access to a computer.
I know an elderly couple in mid 80's who fly quite a lot using every airline and I offered once to help if ever needed on checking in ................now they pretty much keep themselves to themselves but they use Library, 4 other neighbours in same street and kids abroad who check them in and post the tickets. They don't posess a credit card or debit card.