It's pretty easy to tell if a wall is straight, a door closes, a drywall joint is smooth, or a grout line is correct. This work isn't rocket science.
A professional does enough work to get paid and then leaves. They don't have to live with the results.
Sounds like I struck a nerve. You must be a contractor.
I can do *anything* any pro can do and I can do a better job - but - it will take me 20 times as long to finish. I'm not doing it for a paycheck. And I couldn't do it for a paycheck.