alt Hacker NewsUSB-C is only a connector/socket - a device having a USB-C socket does not guarantee much beyond being able to plug a USB-C connector into it.
Some USB-C devices only use the port for charging for example. Others might only support USB 2.0.
Getting a display out from something with USB-C socket needs the device to support something called DP Alt Mode.
Note that cables matter too - you can have a DP alt mode enabled monitor and phone, but if you have the wrong cable it won’t work. Welcome to the future.
It is understandable that every cable doesn't have to and shouldn't support every feature. USB cables would be insaney overpriced in that case. For simple charging you don't need a high speed 40gbps cable that can connect an external GPU.
To mitigate the confusion, all simple charging cables should be universally labeled as such and all high speed cables should also have some markings that indicate the maximum speed of the cable or something similar.