U.S. residents, including temporary residents, are considered "U.S. persons" by the IRS and have to report everything. Amusingly this also applies to holders of U.S. Green Cards who aren't actually resident in the U.S.
Canadians working in the U.S. have had fun with IRS because a type of Canadian registered (tax-advantaged) savings account is not recognized by the IRS as a registered savings account but rather a "passive foreign investment company" and IRS loves to make people fill out lots of paperwork. This is apparently because IRS rules haven't been updated in the 10 years since the account type has been created.
Canadians working in the U.S. have had fun with IRS because a type of Canadian registered (tax-advantaged) savings account is not recognized by the IRS as a registered savings account but rather a "passive foreign investment company" and IRS loves to make people fill out lots of paperwork. This is apparently because IRS rules haven't been updated in the 10 years since the account type has been created.