"IQ tests as a secondary defense to educational transcript fraud". Sure, I guess that works. Might not be the best way to check, but used in that way it's better than many other options. What really matters is how the test are organized and conducted.

(Though it does depend on what the immigrant is claiming to be qualified in - if, as some countries like Australia has done in the past, you are taking in immigrants qualified in service oriented fields, then IQ is maybe not the point.)

Indeed corruption in educational qualifications outside of the "western world" (speaking incredibly vaguely) is a huge problem (and unlike most westerners I speak from direct experience).