From that point of view, I can see why you wouldn't want to be mixing up common with circuit common.

Perhaps it's why we usually call it "ground" instead. That in itself is wrong as it implies a connection to earth, but voltage measurements are relative, not absolute. It's why measurements always must be taken with respect to a reference point.
That point is often - but certainly doesn't have to be!!! - at earth potential.
The latter only works if the device under measurement has been referenced to earth itself (like non galvanically isolated mains powered devices). Introduce isolation via a transformer and now your reference point needs to be shifted.

We actually use 230 V/50 Hz single phase, 400 V threephase in the EU.
This is also a good example to show that voltage measurements are relative. Put the black probe on the neutral (N) conductor and the red one on any of the three phases L1, L2 or L3, and you measure approx. 230 V. Put both probes on any of the L1, L2 or L3 and suddenly the reading is 400 V.
Measured with respect to N, each phase measures at 230 V, but measured with respect to any of the phases, the other two measure 400 V.

BTW, a YT channel explains here that mains voltage in the USA is actually 240 V, not 120 V, despite it coming out of your sockets.