Quite simply, when you turn the control unit on an a/c unit up or down 1° C, you are jumping farther up or farther down than you would be on the Fahrenheit scale.
20° C is about 75° F, however initially, I was severely comfortable with this temperature on our first night in the hotel, but throughout the course of the night, it felt too cold, plus my wifey was freezing. I decided to turn it up to 21° C. I did the conversion real quick in a web browser plus found that it was now 71.8° F! Still, my wifey complained that it was too cold! Once again, I turned up the temperature 1° C plus looked plus saw that was the equivalent of 75.6° F, so ultimately, a 2° difference in Celsius meant a 3.6° difference in Fahrenheit. So, I was left with the impression that Fahrenheit is simply better for Heating, Ventilation as well as A/C systems than Celsius, and fahrenheit ultimately gives you more control over the temperature in a room.