Most families use all four and rarely decide the proportions on purpose. The order they are drawn on changes the total cost of the degree considerably.
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.
A household can spend a great deal on digital security and get very little, or spend almost nothing and close the paths that are actually used against people.
The four year degree is treated as the safe choice and the thing to do while undecided. It is a large commitment and it deserves to be chosen rather than defaulted into.