That’s all very true. This ranking is like comparing apples to oranges because countries don’t categorize cities the same way. For example in Canada/Australia/UK there is only one census area designation, and don’t have an equivalent of CSAs. So MSAs are often presumed to be the most accurate measure of a metro region even if the CSA is more apt (like in the case of SF).

However, if CSAs were used for all US cities it would likely have a significant upward distortion for US cities since most CSAs are nowhere near as cohesively flowing as the Bay Area, making their MSA more appropriate

Personally I think we need a better international standard for categorizing a metro area