How can my car's thermometer possibly be right?

I have a car with an outside temperature reading on the dash. Where in the world could you possibly put a temperature probe on a car that it would give an accurate reading of the outside air? In the summer, the surfaces are hot and the interior spaces within the body would be hot too.

In front of the radiator, behind the grille is a good place to start

On our Sonata, it’s just under the front bumper.

(I just called the dealership and asked.)

Two common locations are under the front bumper and in the outside rear view mirror.
Both can be somewhat inaccurate at times. The one under the front bumper can pick up radiant heat off the pavement causing it to read a bit high, the one in the mirror can be exposed to sunlight and again read a bit high.
for the most part, they are pretty accurate.