It is fundamental to the purpose of the chapter to recognize that many existing lots throughout the city are less adequate than others because of their location or size or odd shape or difficult topography, or any combination of these limitations. A claim of hardship under this chapter, therefore, shall not be allowed on behalf of any lot because the physical characteristics of the lot prevent it from being built upon exactly as in another lot abutting or close to it or in the same zoning district. The regulations herein permit most such lots to be satisfactorily built upon. There can be some alleviation for other lots through variances (minor concessions) granted by the Zoning Hearing Board when special physical conditions make literal enforcement of the regulations either unsatisfactory in the interest of the people at large or actually impossible. It is not the ordinance but the physical conditions that prevent a lot from accommodating a type or area or bulk of structure unsuited to it. For a typical example, it is not intended that each lot in a General Residence District automatically become the prospective site for a multiple-family dwelling and use. If a lot in such a district, after provision of the yards and other open spaces prescribed for its own and adjacent property protection, has a buildable area too small in extent or dimensions for a multiple-family dwelling, then the lot may be used under its district regulations for another type of dwelling or structure permitted in that district.