I could be wrong, but I think it kinda depends on the fill station...
I used to work in a sporting goods store that filled paintball CO2 tanks. The only way to get the customers tank to hold "x" ounces of CO2 (generally 9oz or 20 oz) was to partially fill the tank, then purge the whole thing. This would bring the tank itself down in temp pretty substantially. Once the tank itself was good and cold, you could actually pump the proper amount of liquid CO2 into it.
I could be wrong here, but if I remember my chemistry correctly, there's basically 2 ways you can keep CO2 liquid under normal circumstances... 1) cool it down, or 2) keep it under pressure. The problem with a "warm" tank is, when the liquid CO2 gets pumped into it, it tends to turn to gaseous CO2 because the tank is warm, and not (yet) under enough pressure to keep the CO2 liquid.