They are unfortunate in that they are such a huge business; while customer and user satisfaction is still at the top of their list, nothing will ever be a higher priority than profit (as it should be with a business).
Close, except that zer01 isn't an MVNO. The story about them using AT&T's 3G network was incorrect, the interviewer made some assumptions about what they're doing.
According to them, they've got interconnect agreements that eliminate the need to lease bandwidth the way an MVNO typically does.
All constants are variables.