There is a difference between "drunk" and "under the influence". Further, there really isn't a legal definition of 'drunk'. There are however legal definitions of "under the influence" - using based on blood alcohol levels. "Under the influence" means legal impaired.
I don't want to ride in any vehicle - car, bus, aircraft, etc. - where the person in control is legal impaired due to alcohol or other drugs. I seriously doubt many people would.