That's what I would have thought too Ira. Recently, I purchased an aqua one glass thermometer and stuck it in my tank which is 55 Litres heated with a 100w Aqua One Heater. About four hours later, I took a look at the thermometer and it reads 28º C. I realised it was 2º C over the recommended temperature for my 2 Neons, 4 Dwarf Gouramies, 2 Bronze Corys and 2 Black Phantom tetras. I immediately turned the heater down by 2º C and temperature fell to 26º C, the recommended temperature that the LFS uses. Please note that the thermometer is on the other side of the tank as the heater is, and my Shark 1 is pointed at the heater which is placed at a 45º inclination to improve heat dissipation. This tells me that those thermostats are not perfect, and that it is best to check temperature with a thermometer.
Here is a Pic of the tank I plan to use. It is made out of Acrylic.