When Celestine Omin tried to enter the US on a work visa, he was
grilled by an immigration agent with vague technical questions,
supposedly
to prove he was really a software engineer.
The agent didn't understand his answers, and threatened to exclude
him. Fortunately, other agents called his employer, who verified he
is an engineer.
Regardless of details, it is absurd to ask a professional to prove
his qualifications to someone who knows nothing about per field
as a condition for immigration.
It is pointless anyway. What exactly is the wrong that agent was
trying to prevent? That a company would arrange a work visa for the
CEO's lover? That might be fraud, but there is no need to investigate
such a suspicion at passport control.