Apple put together this pretty detailed product support page for the new MacBook USB-C port and the associated adapters.
Note that the MacBook is referred to as MacBook (Retina, 12-inch, Early 2015).
Apple lays out the details on the USB-C port and adapters
So the USB-C cable that comes with the MacBook is not of the full-featured type and does not support USB-3-data speeds – it’s just for charging.
I did not expect Apple to be so abysmally cheap …
WTF?
WTF, really?
I don’t mind that this MacBook has only one port, as this port is very capable. I even don’t mind that no adapters are in the box, as everybody has different needs. But the one cable that is in the box should live up to the standard that Apple is advertising so strongly.
What, for all the people who will use it that way?
Exactly what percentage do you think that is?
A good many (maybe not most) will want to migrate from their previous MacBook using a cable. Hardwired migration is still much faster than over WiFi.
Squabbles over the included cable aside, it seems to me that Apple’s philosophy is that if the current standards don’t meet their needs they will provide an interim solution that does. When the industry standard meets their requirements they switch. This is expensive for them and sometimes an annoyance for us. Apple also does not provide for every use-case in either their products or peripherals and cables. One should not be surprised at this late date by this. So far this seems to have worked out well all around.
USB 2.0 is fine for a one time migration.
So it supports the new USB 3.1 specs in terms of charging, but not data. Not sure why they would bother with such a cable in the first place.
Pretty sure this whole opting for USB-C thing is a prelude to its adoption on the iPhone. The EU has mandated all mobile handsets must provide a common USB charging port so that there is competition and choice for third party chargers. Apple will have been left with a set of uncomfortable choices. Either create an EU only iPhone model, which goes against their one iPhone ethos, or adopt the incredibly ugly mini-USB 3, or input into a new, more acceptable USB connector design. It seems they opted for the latter – rumour has it they drove the work on the new standard.