Sometimes the same properties market to different segments. There are people who want a large breakfast and want it included in their rate for one reason or another. There are others who may have coffee and a muffin and don't want to subsidize the others.
Then there are business travelers who could care less. They order what they want and are reimbursed. Some people don't want a buffet. They want servers to take their order and bring them what they want.
Bottom line is that breakfast is an enormously profitable enterprise for properties have a restaurant anyway. Same facility, breakfast foods are largely cheap and easy to make, less wait staff required if there is a buffet, and it is a good training ground for staff. On top of it, people willing to pay $50 for a buffet are easy marks.