It is outrageous because in both instances we're talking about actual legal citizens being persecuted by their own government for belonging to an ethnic group, not a group of foreign nationals that illegally entered the country and are being held temporarily for criminal prosecution.
That's irrelevant. The root cause of running a concentration camp is unimportant; they're human beings and deserve to be treated with dignity.
As it stands, the US is failing to hold them to the standards we hold even incarcerated prisoners, and they haven't been convicted of any crime. That's outrageous.
Treating some humans under one's jurisdiction as more "human" because they are citizens is a severe anti-pattern.
"The Japanese internment wasn't that big of a deal" is certainly a claim a person can make, but I don't feel compelled to continue discoursing with someone who does.
The Holocaust wasn't the only situation involving concentration camps in history. The US ran concentration camps during World War II for Japanese-Americans more or less because of racism coupled with fear of espionage or anti-nationalism; that's just fact in terms of the definition of these terms. In fact, when discussing contemporary US policy, it's the most relevant historical comparison.
In addition to running concentration camps (unacceptable), the nazi party also ran forced labor camps and death camps, which distinguishes the horrors they inflicted from the horrors the US inflicted on its Japanese-American population. But to ignore the US's history of depriving liberty from classes of people when it suits us opens up its own can of dangers that is (one hopes) smaller than the dangers of nazi ideology but should not be ignored.
