You can get certified for less than the Fluke classes.
There is a difference between a man and a camera and photographer, a difference between an electrician and someone that can wire, understand and trouble controls, this is no different.
Yes anyone can tell a hot spot from an adjacent pole, but can you tell if a 50 amp CB carrying 29 amps is at an acceptable temperature for the ambient? Or do you just guess away, and possibly look good to the customer or possibly like a fool?
In 40 years working in the trade (28-30 doing IR) I have never put my self out there where I might end up looking like a fool. Just myself, but I have always wanted to be the best I can, and to do that I have always felt that took as much knowledge about the subject matter at hand.