Giving up Green Card less than one year after obtaining

Its really hard to come up with a sceanrio in which a US green card holder (assuming he is able to maintain that status for very long while living in Canada) will end up paying more tax to US, after paying his share in canada, and then taking all the exemptions, credits, deductions on his 1040.

Heck, most couples with kids actually GET an extra $1000 per kid free from the IRS just for filing.