I see a lot of people having trouble with USB-C cables. What exactly happens in this little OTG cable and why won't a USB-C to USB-C cable work? What is the technical difference?

I don't have a good answer for your but I'll add one observation. USB cables can look alike and still be very different internally. I've made it a habit of labeling each new USB cable I receive to know which product it's intended to be used with. The amount of current USB cables can deliver varies and does the amount of data they can transmit. The number of internal conductors varies.

Hopefully someone will provide a better answer but I just thought I'd share the observations I've made about USB cables.

The OTG cable allows a device that is normally a client device, to become a host device, its short for On The Go. There’s a full description on a Wiki.

For the DJI goggles it’s needed when the goggles needs to be a host to your mobile device rather that a client, usually during the activation and firmware update process. You can use USB-C to your device when using the device as a display device without the OTG adapter.

USB-C is not a standard, other than the standard that makes it a connector, how that connector is used is down to individual manufacturers, which hasn’t been this confused since the days of RS-232!

This is why you will find some cables will work with one device but not another, for example, Intels thunderbolt standard uses the USB-C connector, but you need a special Thunderbolt cable to connect two Thunderbolt devices together a just because the cable has USB-C connectors doesn’t mean it will work!
Even DJI have now got a cable that is only for goggles battery!

Hello there Spooky Spirits. Good day and thank you for the inquiry. The OTG allows USB devices, such as tablets or smartphones, to act as a host, allowing other USB devices, such as USB flash drives, digital cameras, mice or keyboards, to be attached to them. For additional reference, I will post a DJI Forum link with regards to this matter as well. Thank you.

https://forum.dji.com/thread-146451-1-1.html