Lots of times the initial screen is done by someone totally non-technical, and they are asking questions from a sheet and judging whether you are saying what is in the answer field for their sheet. This is super stupid, but I have seen it, usually when some headhunting firm is deciding whether to add your resume to their database which they pull resume's from to send to clients.
The moral: Don't use headhunting firms, because they will basically never send you a decent candidate. In the very rare cases where they by pure luck do send a good candidate, this is rarely worth the dozens of crap candidates they have sent you (not to mention that they will try to push candidates on you if they think they can get away with it).