Friction is a force relating to molecular structure of two surfaces touching each other. Molecules from one surface link with molecules from the other. If you press the objects together more tightly, you push the surfaces closer together, joining more molecules. This proportion is the coefficient of friction. Molecules on adjoining surfaces just don't cling to each other strongly enough to have a huge friction coefficient.
Solid molecules prefer to cling to each other rather than other solid materials.
This is pretty much what makes them solid. In theory, there may be some solid materials that cling to each other strongly enough to have a huge coefficient of friction. I just don't know of any. Argonne National Laboratory, Division of Educational Programs, Harold Myron, Ph.D., Division Director.