The inferior U.S. vs. German equipment myth is one that dies hard and was actually started by G.I's. who were returning from the European theater. Most of it revolved around the superior firepower of the German tanks vs. ours, and the inefectiveness of the infantry Bazooka in combating them. That and complaints about the Sherman which earned the ignominious nickname "zippo", because "they light every time" when hit.
Many history books which rely on first-hand stories told by GI's often harp on those points. Added to it was the fact that American soldiers were not well equipped clothing wise for winter combat like the germans (who, by that time, had learned their lessons on this matter on the Russian front where the tables had been turned on them).