You might be right about the exit polls. Perhaps this can only be applied in countries that have strong independent monitors (which Estonia should have being an EU member). Regarding vote selling, I don’t know how it is in Estonia, but in Iceland voter ID is pretty lax. You can provide an ID in the form of passport, drivers license, bank issued debit cards, etc. As a buyer I have no way of knowing if I'm witholding all possible IDs from my agent since they might have several debit cards from several banks, more then one passport (through dual-citizenship), etc.