I see your point. The problem is that the vehicles that had the two speed fans had a control module that regulated everything. The fan speed is never supposed to be as high as it is with just the green wire powered. The way it's supposed to work is that the slow speed is turned on at around 220 degrees, and is turned off around 200. If the temp is above 200, and the fan is on low, and the a/c is turned on, the green wire also receives power, and the fan speed increases. You've got everything correct.
Take care,
~Chris