Electrical design is an art and this why the people who do it charge so much money for their services. Electrical design is to wiring the old domestic plug what flapping of your arms is to flying. These men and women study for years to become that artist that they are. Electrical design is so complex because there are so many factors at work.
When you think about what goes into the electrical design of even a regular home, it is very complex. Knowing where every single wire needs to go for the domestic circuits to work as you want them to is a skill that requires so much precision and such careful planning that most building contractors would not even consider haggling over the price that the person in charge of the electrical design is charging because they know better than any other person, not directly involved with the electrical design, just complex the job is.
Once you have wrapped your brain around the complexity of domestic electrical design than be prepared to have it all blown away again when you consider what is involved in the electrical design of a very large building with say fifty different levels and enough electrical cabling to run to the moon and back so many times that the figure is quite meaningless. The folks who handle this level of electrical design make more money than Croesus and they deserve every penny because it is not ac case: do the job, get paid walk away.
When you are in charge of the electrical design of one of the mega building that are going up in cities everywhere then your commitment and that of your firm is quite a lot more long term than that, because if anything ever goes wrong with the electrical work in the building the schematics that explain the building electrical design needs to be clear and precise because the reputation of the designer and his/her company is on the line as well as much future business and you are only as good as your last job.