For those saying about the Apple three-pin adapters not being earthed (grounded), they do not need to be as they are basically just figure-8 connecters and the power adapters are double insulated instead. The same as most lower powered devices sold in the U.K., and if you really wanted to I am sure a standard figure-8 lead would fit instead of using an official Apple adapter. Though obviously it could be pulled out more easily.
Double insulation is represented by a mark of a square containing another square, so you should see that if you look at an Apple power adapter. Although sometimes they are not easy to see, on my Magsafe adapter it is in the top left corner of the UL Japan certification.
I'm more fascinated that some of these devices would still be in regular service. Even at the top end 2010 is 9 years ago. I'm not still rocking any tech from back then.
I am sure plenty of people use old adapters if they still work, all they are is a set of pins to match an appropriate power outlet. When I need to use one I just grab whatever is nearest.
The cable adapter I mainly use I think is the one from my 2003 PowerBook G4. Though it might be from a mid-2007 MacBook instead.
And not that it uses an adapter, but I still use my 2011 Mac mini in regular service, though my MacBook Pro which I use daily for everything is a late 2013 model. And I still use my iPhone 4 as an iPod from time-to-time, though my main phone is now a very modern iPhone 6.
They all still works well enough for my needs that I have no need to replace them just because there have been superseded several times since.