The question isn't why wage growth is so low, it's why it's so high

In fact, the average hourly earnings for nonmanagerial private sector workers rose 2.4 percent a year in that period. You may not feel like cheering about that, but it’s more than we might have expected, with inflation and productivity so weak. The real mystery, then, isn’t why wages are rising so slowly, but why they’re rising so fast.

If anything, the numbers show that workers are capturing more than their share of the spoils from a growing economy. And that, as it happens, is the reverse of a decades-long trend. For most of the last half-century — 84 percent of the time since 1966 — average wages have grown more slowly than would be predicted based on productivity and inflation growth. The rise in the share of employee compensation that takes the form of health benefits instead of wages is a factor, but doesn’t explain the whole gap; for long stretches, that gap exceeded 2 percentage points a year.

That means the labor share of national income was shrinking, or, more plainly, that workers’ slice of the economic pie got smaller while the part taken by shareholders and other owners of capital grew.