An electric dryer is an inherently unbalanced load because of the drum motor being 120v.
It's like 4kW for the heating element, balanced so 2kW per leg plus maybe .5kW for the motor on one leg.
So that would be 2kW one leg and 2.5kW the other leg.
Figures for example, not actual numbers, I don't know the exact typical numbers for a dryer.
I imagine some of the new heat pump dryers might use inverter motors that take 240v input, so maybe some of those are totally balanced. Or if they're not an inverter motor at least just a total design taken from the 230v market so using a 230v AC motor.