Is a person mere stepping on the platform of a bus already considered a passenger?

Yes. The person, by stepping and standing on the platform of the bus, is already considered a passenger and is entitled all the rights and protection pertaining to such a contractual relation. Hence, it has been held that the duty which the carrier owes to its patrons extends to persons boarding cars as well as to those alighting therefrom (Dangwa vs. CA, G.R. No. 95582, October 7, 1991).