The idea is that the document you swear on has meaning to you. Politicians don’t give a flying fuck about the constitution so long as it lines their wallets and keeps them fat and happy. Swearing on a document is inane and meaningless and it’s 100% for show. It’s meant to keep the people happy for whom the document they are swearing on, holds meaning to in the first place. Make them swear on a signed contract that states, not upholding the written law would mean forfeiting their lives and then maybe it might mean something, as long as there were some enforcement behind that sort of thing.