> Is there a demand in FAANG for programmers but in Europe, and if so how much of a difference is it between US and Europe?
Google, Microsoft and Facebook have large offices in London. They also have offices in Zürich, where the pay is much better, though only Google has a large presence there.
All the FAANG companies will generally hire anyone who passes their interview process as long as the office has open positions (it usually does) but the US generally has much much higher demand than Europe. London is no comparison to the bay area. Not even really the Seattle area.
(Though I'm happy in Europe)
> What would you say is a single trait which differentiates candidates to FAANG? Specific college, programmer from a young age, already established experience or personality, etc.
The ability to, given a reasonable time, solve an enormously broad range of problems (which is what I see the interview process as testing for).
FAANG engineers usually aren't "frontend", "backend", "iOS" or "Android" engineers, they're just "engineers". It's usually expected that they can grab someone from anywhere in the company, put them anywhere else in the company and within ~6 months have them productively contributing code.
Of course there are exceptions to this, like research positions or design/UX engineers but generally that's the expectation.
> And finally, is it true that a lot of candidates are socially inept? I.e. lack interpersonal skills, verbal and non-verbal communication, if so, how big of a role does it play in an interview?
My biggest issue with interview candidates has been people who don't talk. The interview isn't as much about solving the problem as how you solve the problem. If you just hear the problem and start silently coding an answer on the board, that's nice but it won't get you a hire recommendation. I need to know what your thought process was, what other options you considered and why you settled on the implementation you chose. I also deliberately leave the problem somewhat ambiguous so that you have to ask questions.
Usually the people who don't talk aren't socially inept though, they're not comfortable with English.