Somebody collecting three quotes cannot assess the work itself. They can only assess the paperwork, which means the document is doing more selling than the price.
Pricing against a competitor copies their arithmetic without ever seeing it. The number that decides everything is how many hours a year can honestly be billed.
Almost nobody reads the letter properly the first time. These are the questions that follow, roughly in the sequence they occur to the person holding it.
Most questions families get stuck on about school have somebody whose actual job is answering them. The difficulty is knowing which person, and how to ask.