Valid point with respect to PBK - she did have to become a paying member to be able to list it on résumés.
In the case of the NHS, our high-school had covered any registration and cost of branded trinkets they handed out during the award ceremony.
I suppose the key difference is, whether the membership was an invitation extended through a formal process at the high school/college, based on the school’s/faculty selection criteria for NHS, PBK, etc., or whether it was just a sales pitch from an unaffiliated party blanketing a commercial mailing list?