Would you not use "and" here, or does one omit it in certain situations?

The answer

爸爸和媽媽，晚安！

is correct, but currently not accepted. Reported.

Yes it's usually omitted in this situation, just as it can be in english: "mother, father, goodnight" or it can be "mother goodnight, father goodnight" (妈妈 晚安，爸爸 晚安) but you rarely hear "mother and father goodnight" (妈妈 和 爸爸，晚安)

“爸爸和妈妈，晚安” should also be correct

Following the rules 晚安,爸爸妈妈 should be correct, it was marked wrong.

Father and mother sounds like 父母 to me. I would have gotten it right if the English sentence had said dad and mom.

i wrote 爸爸也妈妈,晚安 and it was marked as wrong, despite being their example sentence the other way round literally three exercises earlier

Why didn't this sentence "父亲母亲，晚安" work? 父亲= father and 母亲= mother.

Mine was exactly as the translation shows, just without the exclamation mark -_-

爸爸和妈妈 can also work! It's grammatically correct even if it sounds odd.

爸爸妈妈 was accepted by itself