I can see where the indelible ink is useful for preventing voter fraud. Mistakes get made, even in developed countries. For YEARS after I moved out of the town where I grew up (hell, I moved out of the state altogether, then got married and changed my last name), I was still on the registered voter list, in my hometown, under my maiden name. My mother was continually asked at the polls if she was <myfirstname>. If I'd kept any ID in my maiden name, I could have voted twice. (I never did, of course.)
OTOH, I'd be annoyed at having to walk around all day with a purple finger. It's annoying enough when I go to a club and get my hand stamped and the stamp is still visible the next day after a shower and multiple hand washings. And I hated walking around with ashes on Ash Wednesday.
My state has voter ID laws. When you go to your polling place, you give your street address, then your name, and you present your ID. Your name is then crossed off the list of eligible voters, and you are given a ballot. You fill out the ballot, insert it into a machine, and off you go with your "I Voted" sticker. For me, that's sufficient. (Then again, I have such an unusual last name and such a weird street address that it's highly unlikely someone would try to impersonate me at the polls.
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