Surely if an air conditioner brings an indoor area to a given temperature (and humidity), it doesn't matter what the temperature is outside. So what gives? Is the air conditioner not powerful enough? Do people not want the inside to be as cold as in other locales, since they're used to the heat? The latter would make sense, but then I don't understand why you'd need to be blowing the vents directly at you.

Also with car A/C (or indoor spaces which take in a lot of direct sunlight), hotter days tend to be the result of greater insolation. If direct sunlight is hitting your skin on a clear summer day it has a significant warming effect which you would want to offset with more ambient or active cooling.

For example, you are out walking on cold ground. Your feet get cold while your core stays warm. This is ideal for keeping heat in your core. You may survive where those with "good" circulation would lose heat too fast.

Although this may be due to lower rate of blood circulation, there is another effect independent of circulation rate.

Heat-exchanger effects along limbs depending on the layout of your veins and arteries, which varies among people. The extreme example is penguins, whose feet are on ice yet their bodies retain heat because of heat exchange as blood circulates in their legs. It maintains a temperature differential along the legs. I'm not suggesting people have specific anatomical structure like penguins, rather I'm saying the natural variation in the placement of veins and arteries in human limbs will result in a range of heat-exchange factors among different people, which is a separate factor from circulation rate, and may indicates a thermally efficient body for some situations.