Essentially the study proves that Trinidadian commuters are rational actors. If public transportation and walking infrastructure are both inadequate, the average commuter will choose to own a vehicle.
They did a study a few years ago and their conclusion was that we doh wanna use busses, cuz we wanna own cars.
Ignoring that, largely, you MUST own a car to reach anywhere reliably in T&T. Cuz the Bus certainly isn't reliable.