Because the US hadn't adopted black-out procedures along the coast, the Germans were able to lie in wait until ships showed up and silhouetted themselves against the shore lights.
Growing up in Miami during the mid/late forties and into the 50’s, we always took terintine to the beach with us to clean off the tar from so many sunken ships just off the cost.
My boss back in the 70’s when I worked for a German company was a captured U boat commander who scuttled his boat but was captured by the Canadians early in the war. He became a Canadian citizen and was generally a good guy, but I think he suffered some grief by the other Germans for surrendering too easily. Most of the other German crews went to the bottom as the war went on.