In Kelly v. City of San Diego (1944) 63 Cal. App. 2d 638, the court struck down a tax on persons living in house trailers within the city limits, but not on persons living in other forms of housing. The court held: "We can see no valid distinction, for the purpose of classification, between the occupancy of a trailer and the occupancy of a permanent structure except perhaps the greater comfort and convenience of the latter and the higher rent paid." (Kelly v. City of San Diego, supra, 63 Cal. App. 2d 638, 643-644.) The city argued that the distinction was valid because persons living in trailers had not paid property taxes while dwellers in houses, apartments, hotels and lodging houses contributed to the financial support of the city by paying rent to landlords who, in turn, used a portion of the rent to pay taxes. In rejecting this argument, the court pointed out that persons owning the property on which a trailer is located also pay property taxes. (Id. at pp. 641-642.) The court also found that it was irrelevant the method of taxation used on trailers was different from the method of taxation used on permanent structures. It found that tax was not a property tax, but a tax on occupancy, and the fact that the property owners were subject to different methods of taxation could not be used to distinguish between property occupants. (Id. at pp. 643-644.)