With all due respect, that's incorrect. Germans were interned and sent to camps as well - and so were Italians. The untold story of German-American internment
That's only one reference, and here's a quote from another source, "The World War II experience of thousands of German Americans, to most, is an unknown."
World War II - The internment of German American civilians
I remember hearing that FDR wanted to round up the German-Americans too but that there were too many of them.
While relocation was far from an ideal solution, there were ways of avoiding it, moving out of the exclusion zone. War is always Hell and mistakes are always made. However, my husband's great-uncle ran one of the relocation camps in AZ. His wife tells of the excellent treatment those living there received. They weren't marched to death and they weren't put in ovens.
Nothing is ideal in this world, but life could have been much worse for those who were relocated.