The construction and maintenance of all such bus passenger shelters shall be deemed to be for the use and convenience of the public, but nothing in this section or in sections 2, 3 or 4 shall be construed to grant any rights whatsoever to any person, firm, corporation or municipality whatsoever or to impair in any way any existing rights granted in accordance with the constitution or laws of this state, but shall be construed as a regulation of the exercise of all such rights.