Whether or not any stage, auto stage, or other motor vehicle is being, or is proposed to be operated as a passenger stage corporation “between fixed termini or over a regular route” within the meaning of this part is a question of fact, and the finding of the commission thereon is final and is not subject to review. Any act of transporting or attempting to transport any person or persons by stage, auto stage, or other motor vehicle upon a public highway of this State between two or more points not both within the limits of a single city or city and county, where the rate, charge, or fare for such transportation is computed, collected, or demanded on an individual fare basis,
shall be presumed to be an act of operating as a passenger stage corporation within the meaning of this part.