I think the problem with tech interviews is that that big companies have a huge pool of mid-level talent to choose from and they choose candidates from that pool essentially arbitrarily. They don't try to distinguish between a very good developer and an extremely good developer... The interviewers themselves are rarely that good themselves so they don't even know what an exceptional developer might look like. If the interviewer likes your personality, your odds are much higher. Also, applying multiple times can help.