Power buttons are easy to find, they are on the front panel of the PC
yes, under the desk, behind someone's handbag.
Or two PCs stacked on top of a filing cabinet. You press a button and realize 0.1 seconds too late you've just shut down someone else's PC.
Or four PCs connected to a KVM switch. Tip: coloured cable ties are very useful. Cable ID you can see from any direction.