Flat rate is not a way to pack prices, but a way to present pricing. When you buy a hamburger, you do not pay separate for the labor & materials.
Flat rate is easier for techs because there are no calculations or worrying about customers watching the clock.
Don’t wait to start offering flat rate until every tasks is perfect. There are methods for quickly pricing or adjusting as you go.
Contractors hesitate because of the fear of that one neverending job where they would lose money. One job is balanced by others.
Many contractors spend 100’s of hours creating their own flat rate system, which often never gets implemented. What a waste!
Some put off updates because of the expense, but a flat rate investment has an almost immediate return.