Basically ‘duty cycle’…same reason electric heaters all put out 1500W but ones for larger rooms are ‘larger’. Big or small, they both put out 1500W, but the small ones can only do it for a few minutes at a time before having to cool off, while the larger ones can run for longer and heat up a big room more quickly.
To be fair, it is the united ´states´, not the united ´people living on the continent´. It wouldn’t be any more fair if California was making the decisions for 20 other states, just because they happen to have a crap load of people. The federal government is kind of supposed to be making decisions and maintaining things between states, not all these decisions affecting the people so directly.