I doubt many Germans, Japanese or Italians were allowed into the US during WW2 (POWs excepted). Besides interning Japanese, Roosevelt also interned some Italians (more narrow scope and many fewer).
Many German people came under US government scrutiny during WW1. There were some spies and saboteurs, but (for obvious reasons) many more were checked out than were found to be spies. German-speaking citizens also experienced violence and riots.
Reality isn't idyllic, and sometimes it sucks.