Most plumbers either bid a job or flat rate it.
There is only so much time in the day for making large lists of items, pricing them, typing them, jeeze, if plumbers wanted to go white collar, they would have stayed in school.
The only way I would do Time and Material, is if the homeowener would pay me for all of that book work.
I have had some jobs that would have taken an extra eight hours to compile a list.
Most things we do so often, we can just look at it and know what it should be.
When I go to a resturant, I read the menu and order.
Bam! There's the price, and I want it!