How does this compare to what regular semis can carry as far as weight of a single trailer legally?

Because if they have to make double or triple trips then cheaper electric is negated.

Apparently. Copy paste.

The maximum weight limit on designated state and local streets and highways is 20,000 pounds on a single axle; 34,000 pounds on a tandem; and up to 80,000 pounds on a 5-axle combination, depending upon axle spacings.

Copy paste.

80,000 pounds

Federal law controls maximum gross vehicle weights and axle loads on the Interstate System. Federal limits are 80,000 pounds gross vehicle weight, 20,000 pounds on a single axle, and 34,000 pounds on a tandem axle group.