All factions can hotkey max to any system. Look at your key binds.
You're confusing basic power management settings with Power Shunt, which as the OP described is a unique feature for shieldless ships. It took a little bit of time in practice for me to notice it, but I got it before I started playing for real, though I feel I only fully started to use it properly lately as I changed how the shunt and shield button works (combo instead of hold), allowing me to fly on max engines 90% of the time and then keep shunting power to weapons when I need it.
