What has age or marital status have to do with being able to do a job competently?  The latter may have something to do with the salary and benefits offered as often compensation offered for females is lower because they are perceived to have a man or family to help support them (they are still doing the same job, but they aren't being compensated equally for it in such cases).

As for age, can't that be judged generally on appearance?  In the GCC because so many of us are expats, health/medical and just the ability to get a visa also play a role in this area, but that can be determined exactly when it comes to the visa application process as it is a requirement of the government, not the company.

And, as you point out MBR, I would be one of those who walked away from an interview which asked about my age, my maritial status, etc. because it is obvious the company is not primarily interested in getting the best qualified and most competent person for the job and as such are unlikely to treat me any better once I'm on the payroll.