> "Defining exploitation as being overcharged relative to the market value of a property"
The ratio they've based their narrative on is called GRM (gross rent multiplier): https://en.m.wikipedia.org/wiki/Gross_Rent_Multiplier
GRM is one of many factors when analyzing investment options. Other important factors include appreciation and expenses (maintenance, property management, etc). Cap rates are a better indicator than GRM (because they include expenses) but still not comparable across asset classes due to appreciation (HCOL++) and unaccounted overhead (LCOL--).
I own both (LCOL oil region, HCOL tech region). If the numbers were equal anyone would only choose the tech region, because of urbanization and future expectations for those industries. It's the same reason P/E ratios on tech stocks are so much higher than on oil stocks. So cap rates are higher on my LCOL oil region properties (approx 6, vs 4 in the tech region). But that's just market forces. If cap rates were equal why would anybody buy in the oil region? Even if you exclude the market's predictions for the future (oil vs tech), the LCOL has additional overhead (more properties at equal value).
Reducing the conversation to cap rates and ESPECIALLY reducing the conversation to GRM - relabeling GRM to "exploitation ratio" - shows these prestigious authors (MIT & Princeton) aren't interested in answering any real questions. They're too smart to believe GRM indicates exploitation. They therefore must have an agenda.
The most interesting question raised is who funded their study, else why are they spending their time forging this narrative?