For many a datacenter - balancing the loads across the three-phase power supply is one area that makes one of, if not the biggest difference in the bill/power charged for using. Though that for many a tech, is an area they are more inclined to overlook.

Then quality of the power (clean sine or noise spikes) auditing, then the factor that UPS's do square wave. Though that's more stability and indeed longevity of your kit plugged that appreciates those nuances.

It is one big rabbit hole and can imagine the likes of Google having dedicated teams to focus just on power optimisations as the dividends at that scale - more than pay for the team.