Why doesn't the Apple-supplied USB charging cable work?
Can you imagine if AC power had the same plug for both 110V and 220V? And you just had to "guess" which one was the right one?
That's a common problem with power supplies that require setting a hard switch to choose between 110V and 220V.
It's hard to see the profusion of semi- and incompatibilities permissible in the USB-C connector as anything but a regression.
On that note, always look on the back for a manual switch. Just to be safe. Its unlikely a regular consumer would need to but I'm learning to change my habits.
The Apple-supplied cable is probably a USB 2.0 cable, with a chip indicating it can handle 5A.
https://www.wired.com/2011/06/thunderbolt-cable-teardown-rev...
Thunderbolt 2 had the same compatibility issue in that it was the same connector as Mini DisplayPort but couldn't run over a standard DP cable. That was pretty minor since it's not like everyone has a pile of loose DP cables sitting around.
On the other hand, your average consumer never uses a Thunderbolt device to begin with on account of them being significantly more expensive than other accessories. They'll likely never run into this even with it using a USB-like cable, and the people who do need TB will figure it out.
Thunderbolt displays can do hubs at full speed, the 5K LG Ultrafine has 3x USB 3.1 gen 1, which IIRC means up to 5 Gbps (vs 480 Mbps for USB 2).
Not sure why your comment was marked [dead] but I just vouched it so it should be back.