Secondly, people are ignoring the fact that RSUs at the 3 companies mentioned (and a few others AMZN/MSFT) have grown substantially in the past 5 years (about 125-150% on average) and is the biggest factor in these "surreal" figures.
Broken down into base (110k starting common at BigCorp), RSUs (initially 100-150K over 4 years) and bonus (10-20% base comp ), these numbers would make more sense. First year total comp is close to 145K-170K. By the time you are a senior engineer (mid-level) and assuming this took 5 years, your base comp is close to 135-160K, with refresher grants (and accounting for market performance) your RSUs probably hit 100K/year, bonuses at 30K bringing total comp to 265K-290K.
I happen to work for a BigCorp in SV (close to 1.5 years now) whose stock is performing poorly, hence my total comp is 160K (110K base, 25K bonus, 25K in RSUs/year). But if we had FB/AMZN/NFLX type of stock performance, then my comp would shoot up to 185K without any promotions.