In part because they work with those parts of their home so often. Many people will never do any work to a roof, or climb up there, making the details of roof repair to homeowners all over the world.
The roof repair firms have specialists who are able to talk to customers and prospective clients about anything that might make the roof seem more familiar to the people that are not able to do the work on it themselves. In the event that you do not possess the knowledge or the tools to patch small roof leaks however, the expense will usually be worth it. Roofers are able to talk with them about the cost to put in flashing, how much to fix roof leak issues as well as other issues that are common.
Since not every customer has roofing made of steel, only some will be in a position to determine the costs of repairing it. Still, these roofs will possess their own particular issues and roofing professionals are aware of every aspect. They will be able to tell which roofing issue is likely to occur on nearly any roof type.