Luckily this is not true. It is often possible to represent the behavior of complex real objects in one of two ways. The first is used when the behavior of the object is almost, but not quite, like the idealized stuff from class. For instance, the frictional force ideally depends only on the normal, or squeezing, force between the objects. In the case of car tires this is not really correct.
Wider tires do generate more frictional force all other things being equal.
We could determine the additional factor by making measurements of the frictional forces generated by a number of tires of differing widths. It might be even more complicated if the actual frictional force also depends on the tire load. This would require another correction factor. At other times the real object has different types of behavior at different points in the process. Under these circumstances we can say that the object behaves like one idealized object for a while and then, at a identifiable point, changes and acts like a different ideal object.