The most "instrusive" so far have been British operators with questions about my ethnicity, religion and sexual orientation and a few weird questions I had never been asked before.
Banana Joe, are you British, or of another nationality?
I ask this as if you're not a Brit I can totally understand why these questions are awkward and intrusive. However, under UK law, and to the best of my knowledge, these questions are asked and then kept totally separate to all other data the company holds about you. Doing this means that should any discrimination then be raised by you for any racism, sexual, religion etc the company can check your original submission. These same very questions also prevent the organisation from the possibility of hiring people in a discriminatory manor. It is quite intrusive, i'll give it that. But it's been about in the UK for years.