I am really insulted by that comment!
Sure, tiling is easy until your tile job fails due to lack of proper preperation and/or application. What deflection criteria did you use and at what live load level, L/360, L/240 - 40, 30 20 or 10 psf? How long did you let the thinset slake for?
How much is your free time worth (obviously less than $45 per hour) How long did it take you to prep the floor and install the tile? how long did it take you to research the proper techniques for doing so. In total how much time and money was spent? You apparently have the free time and skill to do a tile job. most professionals making $60K plus per year and working 40 or more hours per week don't I have MANY repeat customers that pay me $55-70 per hour for tiling, plumbing, etc because: i guarantee my work, I disrupt my clients lives as little as possible, do outstanding work, etc etc.
Is a doctor a thief becuase he/she charges you $150 for a 10 min visit to his/her PA for a prescription for antibiotics?