> The methodology's way to assign numeric values to things doesn't relate to intrinsic things about the objects under study

Keep reading. They explain the intrinsic things that make up the numbers they assign to the objects. Eg:

"Each country’s property rights score is assessed according to the following criteria:

    100—Private property is guaranteed by the government. The court system enforces contracts efficiently and quickly. The justice system punishes those who unlawfully confiscate private property. There is no corruption or expropriation.

    90—Private property is guaranteed by the government. The court system enforces contracts efficiently. The justice system punishes those who unlawfully confiscate private property. Corruption is nearly nonexistent, and expropriation is highly unlikely."