[quietpain]

In Europe the entire mains grid is synchronised - the smallest deviation in fase & frequency is the same. It’s fairly straightforward to sync them with this distributed reference clock.

Edit: https://www.mainsfrequency.com/

[jcalvinowens]

The frequency observed across all loads in the system might be very consistent, but the phase is absolutely not. Different types of transformers introduce different phase shifts, so this can't work.