Well I think ??? ???? ???? ??? ???? is relevant here, for two reasons:
1. There is no reason to assume definitely that every knife is used every day.
2. The concept is not based on a ???, it is based on a sfek sfeika (safek it was not used, even if it was, safek the item it was used for is pogem b’ein.). So we don’t need to say it probably wasn’t used, there just needs to be a safek.