Here is another possibility; the difference is multiple processors gives the 1D X many times the 7D's processing power in camera, plus it costs an extra $5,300 and it should do more.

Let’s not forget the advancements in firmware, and Canon’s marketing making sure a $1,500 camera doesn’t out perform its flag ship body.

When the 1D X was released I went in to the ISO Charts make a few comparisons. What I found is that the ISO Charts are good at comparing lenses, but because of the way ISO charts are made they are really not ideal for comparing camera bodies. It is not a fair comparison.