Canon's new 61 pt AF system (1DX, 5D3) smokes Nikon

My 5D3 and 50 1.2L focuses better than when it was on my 5D2, but still not as good as I'd hoped. What is the difficulty in making a fast fifty focus reliably for Canon? (Yes, I understand small depth of field.... I'm talking focusing 2 feet in front). Number of keepers better, but still doesn't match my other L lenses.