No. If the resistance per foot of the cord is Rl, then the power loss per foot, which shows up as heat, at 15 amps is 225xRl. If you run 20 amps through the cord the loss becomes 400xRl, so the cord will tend to get warm. At 75 amps you get 5625xRl, and probably burn the house down. Now in reality the current rating is rather conservative, because the manufacturer realizes that there is a strong possibility that someone will run the cord under a carpet. But 75 amps is out of the ball park in any case.