(1) No driver or operator of any class A or class B motor vehicle used in the transportation of passengers shall refuse to carry any person offering himself or herself at any regular stopping place for carriage and who tenders the regular fare to any regular stopping place on the route of said motor vehicle, or between the terminals thereof, if allowed to carry passengers to such point under the certificate for such route, unless at the time of such offer the seats of said motor vehicle are fully occupied; provided, however, that the driver or operator of such motor vehicle may refuse transportation to any person who is in an intoxicated condition or conducting himself in a boisterous or disorderly manner.