Question about Grand Canyon SFRA / Part 93 Subpart U

The sectional says "VFR Flight through the Grand Canyon Special Flight Rules area (GCN SFRA) is NOT AUTHORIZED except through designated corridors ..." and then refers to the Grand Canyon VFR chart.

• On that Grand Canyon VFR chart that box is missing. Why? If it's good for the sectional it should be good for the "special" Grand Canyon VFR chart that has more focus.
• I have my doubts that sentence is actually true in its literal meaning. That sentence phrased differently says that all VFR flight through the SFRA *MUST* be through corridors. Which would also mean: If it's through the SFRA but not through corridors it's illegal. That would, for example make a direct flight from KGCN to L25 impossible, because that's through the SFRA area but not on corridors.

What am I missing?