Similar to this, federal tax withholding is poorly understand by many people. A lot of people want to give the govt an interest free loan every year and don't understand why anyone wouldn't.

Absolutely. I recently explained this to my retiree mother-in-law who was overpaying taxes each year for fear that she'd owe money at the end of the tax year, forgetting that every dollar she overpays is another dollar she's drawing down from her saving that isn't earning (modest) interest.

Not that I can claim I'm being any smarter. I really should instruct my employer to reduce my tax withholdings, as I'm saving into a tax advantaged account to which contributions result in an income deduction. Every dollar I get at the end of the tax year in a refund is a dollar I'm not saving during the year (thus losing out on some long-term gains).

But at least I know better. ;)