The thing I have found is that folks will come to you and ask for a price, then wander off muttering, you sometimes get to talk to them later and they complain about the cut rate job, when you tell them you can't expect great service for what they paid, they admit that they knew that, but, thought since they were paying less, they might get less, but, not that much less. You ask them how they could have thought for $5 a head from a taco truck they thought it would compare to $40 a head from a caterer and they will tell you they think it just isn't that hard.
We have become a culture of people that simply over-value what we do and under-value what others do. I continue to be amazed at all the people that tell me that their time is worth hundreds of dollars an hour to them and then complain that paying me $100 an hour is outrageous just to design a garden.