I'd quite like to see USB-C sockets on trains at some point. Decent power when done right and no fear of mangling ports or incorrectly plugging things in either. Sadly we're still in wall wart and USB-B territory while phone and laptop manufacturers continue to hold back against full adoption of USB-C.
I do like the idea, however, they will still limit the output of the USB-C to at most 2A (most probably 1A). Otherwise the overall current to power more than one socket would become problematic with regard to guages. Remember, the cable "guage" is related to current, not . so having 6 2A USB sockets would require a wire capable of 12A max (close to the 13A required for an electric heater/kettle).
So unless there is a transformer on every socket pair, and a higher voltage line used as the common power, they woudl need to limit the current draw somewhat. Plus there is the health and safety aspect with regards to people pluggin silly things they can overload circuits and wires, hence why most public USB ports are restricted in power.
Unlikely you are going to soon be able to charge your laptop on a public USC-C port, hence the requirement for standard 240v sockets.
The socket on the "host" device, in this case the power adapter, is a USB-A type.
USB-C allows both the host and device to be USB-C connectors. The USB-A plug is no longer needed for the host (though is still used a lot due to legacy)