[FriedPickles]

Exactly. The Apple extension cord is grounded. They likely didn't include a grounding pin on the stock adapter because (1) it'd be really hard to make it fold down and (2) you lose the option of which direction to plug it in (potentially blocking a plug). So it's a design call.

[aetherspawn]

Note only USA adapters are bi-directional like you say.

[tharkun__]

Wrong.

https://www.adapterelaptop.com/images/Apple-61W-USB-C.jpg

[cbluth]

Note that that plug is not grounded, and eu plugs thatare grounded are also bidirectional, unlike us grounded plugs

[deepsummer]

Depends. German are, French are not bidirectional.

[candiodari]

Even the bidirectional ones (with the little "tabs") are WAY more massive than the ungrounded plugs.