Power over Ethernet can't do 100W. The 802.3bt supports 51W (Type 3) or 71W (Type 2). PoE uses pretty small currents, Type 4 is 960mA.
Also, PoE does have significant loss over longer distances. It isn't a problem with low power devices but would be a huge issue for higher power. It is almost certainly more efficient to send power as 120V AC and convert to USB-C.
The alternative is outlets with USB-C ports, or power strips with USB-C.
Places that use 12V/48V DC have much thicker cables. They also have shorter lengths on RV, boat, or cabin.
Also, PoE does have significant loss over longer distances. It isn't a problem with low power devices but would be a huge issue for higher power. It is almost certainly more efficient to send power as 120V AC and convert to USB-C.
The alternative is outlets with USB-C ports, or power strips with USB-C.
Places that use 12V/48V DC have much thicker cables. They also have shorter lengths on RV, boat, or cabin.