In connection with any redevelopment located, wholly or partly, within the area in which it is authorized to act, any city, borough, town, township or county may contract with a redevelopment authority or the Federal government with respect to any sums which the redevelopment authority or the Federal government may agree to pay during any year or period of years to such city, borough, town, township or county for the improvements, services and facilities to be provided by it for the benefit of said redevelopment or the persons occupying such area: Provided, however, That the absence of a contract for such payments shall in no way relieve cities, boroughs, towns, townships and counties from the duty to furnish for the benefit of said redevelopment and the persons occupying said area, customary improvements and such services and facilities as cities, boroughs, towns, townships and counties respectively usually furnish without a service fee.