Because of the size of showers they are simply too daunting to consider replacing. Tile and grout surfaces can become very hard to deal with over time; tiles become outdated or cracked, grout can become loose, cracked or missing entirely. Whether tile, fiberglass or solid surface they all would require major demolition just to remove them. New tile work is a large project that requires an extended time commitment. Fiberglass showers are very difficult to replace and are often an odd size impossible to locate. Most of this these types of showers are installed before your walls when your house is built. All of these surfaces require major remodeling to deal with but when you refinish these old surfaces are updated and returned to use very quickly.