travel agent
Box office clerk
conductor
They might be a ticketing agent, an office clerk, or a scalper.
You would call it a ticket office or a ticket broker.
An author is a person who writes and sells books.
The person who sells drink is known as sellsmen
baker
A person who sells books is commonly referred to as a bookseller or a book vendor.
You call a person who sells flowers a (Florist)
A "Pilot" is a person who drives a plane.
A person who sells ship supplies is called a chandler
A person who sells jewels is called a jeweler.