Speaking of which, can some electrician please explain why Apple chargers (for USA) use ungrounded plugs while every computer I've ever owned uses grounded plugs?
This is the case in many places outside of the US as well, as far as I can tell. The included extension cord (C5?) was grounded at least for my last MacBook years ago, but they provide a non-grounded connector probably because it's less bulky (easier to design as a folding mechanism) and more universal (especially in continental Europe where the two-prong is nearly universal and the third prong is far from that).
It's also not just Apple. Lower wattage Lenovo chargers (including ThinkPad) have two-prong adapters and plugs.
It's also not just Apple. Lower wattage Lenovo chargers (including ThinkPad) have two-prong adapters and plugs.