'Bound to secrecy': The indelible ink behind the biggest election

I once would have thought Americans would never go for something like this, but with the levels of crying wolf around voting, a finger mark as a tangible mark to stop double voting seems quite logical and something that everyone can understand and enforce.

Eg I could quietly check the people standing in line with me as we line up, as could each official more explicitly ask to show your finger on the way in, and there’s no benefit to faking a mark.