In 'The Bell Curve' is an appendix which claims to explain the tortured
history of using tests (including IQ) as a method of employee selection. It
would appear that all tests on which blacks score lower than whites on the
average have been banned, as being discriminatory. This doesn't explain why
IQ scores do not appear on resumes outside the US, however.
I say 'claims to explain' because I no longer trust 'The Bell Curve' to tell
the balanced truth. I've seen enough criticism of it to believe that it is
as slanted as possible without actually telling barefaced lies.