A 10% skill difference between two people with shovels will result in a much smaller output difference than a 10% skill difference between two operators of heavy duty earth moving equipment.
With software, this dynamic occurs in the extreme, as the cost to run a software program is so low. A hour of unskilled human labor cost hundreds or thousands of times more than an hour of computation. And the quantity and complexity of output from a single hour of computation is rapidly increasing.
Edit: reworked the comment to make my point much more clearly
Of course with bad managers it can easily go the same amount in the other direction, but it seems that Bezos has extremely effectively leveraged his abilities in management and built a very successful company because of that.
One of them made a hole in the ground; he's going to put a seed in it, which will hopefully grow into something useful.
The other one pushed a button which started an automatic lathe which created an engine piston worth a hundred thousand dollars.
The difference in the productivity of two people is practically limitless.