While that cost difference is stark, proponents note that the payment amounts do not take into account that those treated with protons tend to have fewer side effects, from secondary cancers to rectal bleeding.
I agree that the data on protons is laughable. Also, the dose uncertainties of protons are not a small issue. What you see on your plan (with only 2 fields) may not represent reality. There is a good Red J editorial on this. That being said, the SEER study however does have many issues as discussed in the editorials in JAMA. I can't really imagine protons being worse. I also can't imagine it being better.