Can Disabled Americans use their handicapped parking passes in other countries?

No. They are issued in the U.S. for use in the U.S. and are invalid outside the country.

No.

The pass isn't valid in any other countries.
The person MAY qualify for the equivalent issued by the other country.

No

They can try but, they are not recognized anywhere except in the country where they were issued. So they'd be laughed at, and ticketed, hauled off to jail anyway.