Per capita is literally per man, woman, child, and grandparent out there. Wages are per one of those engaged in work. As already noted, today we have more workers per capita than we used to. That counterbalances those figures somewhat.
Furthermore note that wages are a poor proxy for personal wealth. Compare two households. One has the father working while the mother cooks, cleans, and takes care of the children. The other has both parents working and also absorbs considerable costs for fast food, daycare, and various other extra costs that the first household does not.
Which is better off? Which looks better in the statistics?
The second one has to make a lot more money than the first just to achieve the same standard of living. It can make a lot less money but still be better off in real terms. But the numbers look nicer when you have families like the second around. The point being that domestic chores don't enter the GNP and don't show up as money and products changing hands. The work is still being done. Food is served, kids are taken care of. But it doesn't exist on the radar of the economic statistics.
Now when comparing the 60's to the present, this factor is not to be ignored lightly. And when looking at income disparity, note that a move from one to 2 income families is going to rob a much larger fraction of personal wealth at the low side of the income barrier than it will for the best off. Therefore the increase in average income is not nearly what the statistics show, and the increase in disparity in real wealth is worse than they say.
Remember, there are lies, damned lies, and statistics...
Cheers,
Ben