You're correct. Professor can be a proper title before someone's name (e.g. Professor Johnson) just like Dr. Johnson, Senator Johnson, President Johnson. However, the job titles teacher, instructor, tutor, postman, and many others are not used as a proper title with someone's name, so you would simply call him Mr. Johnson.
Saying "Mr./Madam + [job title]" is reserved for only certain positions to show respect, usually a high ranking politician - Mr. Secretary (for the Secretary of State in the US), Madam President, Mr. Ambassador, etc.