Although Germans were not sent to internment camps like the Japanese, there were still many cases of Germans being targeted by the United States government and forcibly relocated.

First, however, let's break down why the Japanese were specifically sent to internment camps. There are a few explanations. In Brian Masaru Hayashi's Democratizing the Enemy: The Japanese American Internment, he writes of race on one hand, and culture and loyalty on the other. For race, the Japanese were targets due to the fact they were non-white. In Stephen Fox's America's Invisible Gulag: A Biography of German American Internment & Exclusion in World War II: Memory & History, Fox also mentions the racial aspect, and writes that the government did not trust Japanese communities like they trusted German or Italian communities. They felt that they "knew" the Germans and Italians more than the Japanese. On a cultural/loyalty level, it was thought that the Japanese had another loyalty towards Emperor Hirohito and Imperial Japan instead of America. There was a distrust among Japanese communities that they would aid and help Japan in the war, and there was an immense fear that there would be an invasion on the West Coast. Although it would be nearly impossible to successfully invade the West Coast, it was still prevalent. It can be argued that even questions of supposed disloyalty and cultural differences as main causes of internment fall under the umbrella of American racism.

Taking this into consideration, there are a few reasons as to why the Germans were not targeted on the same level as the Japanese. As mentioned, race was a huge factor in this. The Germans were trusted more than the Japanese, they were seen as more civilized and were perceived as closer to Americans than the Japanese were. And second, there was never a German attack on American soil. Pearl Harbor was a traumatic event for Americans, and struck a deep fear into the public psyche. Nazi Germany never did something like that, and so there was less public anger or fear.

With all this said, there were still German Americans interned or relocated. The American government chose a strategy of selective internment for German Americas, targeting leaders and active members of German American organizations and individuals they deemed a risk to security. King writes of this in America's Invisible Gulag, and emphasizes that the government did not want to alarm the American public and did not want to hinder the war effort by targeting millions of German Americans. By selectively targeting German Americans, they could "pacify" the rest of them. There was also a governmental fear that Germany would retaliate against captured Americans if there was any mass internment. So, the Germans were still targeted and relocated or jailed, but there was never a mass internment like the Japanese.

I hope this adequately answers your question!