The simple answer to this is that contact lenses require more time to fit. It may take several visits to teach you how to get the lenses in and out, then return visits after the patient has been using the lenses in the real world before a final prescription can be confirmed. All that is usually covered in the cost of an initial contact lens fitting.
Because they are more difficult than the simple eye glasses exam,and the professional will take more time to care about the patient.and the eye doctor spend many years to bring out the examination,and investment much money on the equipment.
The correct answer is because it takes a fair amount of time to carry out the examination-and a lot of investment in equipment to just provide the service-never mind the length of time it takes to qualify as a competent professional. But what your practitioner did wasn't worth that at all - I've heard that done often. I find it weird that in a country as litigious as the US people still "fit" contact lenses that way. She has no idea if the lenses actually fit your eyes and how comfortable they are - never mind the detailed look at the cornea and surrounding parts of the eye that a proper contact lens fitting takes - she just took some extra money from you and took the lazy way out.