Couldn't you build a charger with high capacity that detects the device and delivers the appropriate output? I can imagine it's not that much more expensive than a standard charger and would be a great selling point.
The problem is, that a more powerful charger needs to be physically bigger. 65W Mac charger is definitely a lot bigger and heavier than a 5W iphone charger. So you can't make iphone chargers which are still very small, yet can charge MacBooks when needed.
This was still infinitely more useful than my SO's Macbook/iPhone combo during the hurricane that knocked out power to my city for about 5 days. (90% lost power for some amount of time while around 20% still didn't have electricity 5 days later, my SO included. I didn't cover the recovery schedule after that.) While I was able to charge my laptop completely on a mobile power bank they was relegated to their phone until we were able to find a hotel with power restored to charge it at. Again, it's not like people will just be able to carry around one cable "to rule them all" but they will have a lot more utility with just the one cable than they used to.
Not sure if you can call this "working", which was gambiting's point.
I was able to fully charge my laptop from a power bank using a phone's USB cable while everyone else was relegated to simply using their phones and waiting for power restoration. What is not "working" about that?
I'm not sure your mother would have as much difficulty differentiating something the size of a laptop charger from something the size of a phone charger... It's not like laptops are going to start shipping with phone-sized chargers all of a sudden.
It's marginally larger than a normal phone charger. Side by side, it's only slightly bigger than Apple ipad charger.
Like you said, "case in point", phone and laptop chargers aren't really going to be getting confused. I think the point you made about your mother is very valid, because a QuickCharge supported charger and a typical standard USB charger will look almost identical, not just in connector shape, but also in absolute size. I agree that adding tablet chargers to the mix confuses that even more. I don't believe that is the case when it comes to laptop chargers vs phone chargers. They are very different in size (both cable and adapter size). They also ship with different products; it's easy to think phone charger, same shape, same size, they do the same thing. I don't know if that will hold true when the chargers are less similar.
I would imagine people will understand "small charger, long charge - big charger, short charge", kinda like they do now, regardless of connector shape. You're right in implying that there is a big difference between tech savvy users and the typical consumer, so maybe I'm completely wrong.