How exactly did movie product placement work before the 90's?

Here is a study done of Tobacco product placement:

"…Results: Both the entertainment and tobacco industries recognised the high value of promotion of tobacco through entertainment media. The 1980s saw undertakings by four tobacco companies, Philip Morris, RJ Reynolds (RJR), American Tobacco Company, and Brown and Williamson to place their products in movies. RJR and Philip Morris also worked to place products on television at the beginning of the decade. Each company hired aggressive product placement firms to represent its interests in Hollywood. These firms placed products and tobacco signage in positive situations that would encourage viewers to use tobacco and kept brands from being used in negative situations. At least one of the companies, RJR, undertook an extensive campaign to hook Hollywood on tobacco by providing free cigarettes to actors on a monthly basis. Efforts were also made to place favourable articles relating to product use by actors in national print media and to encourage professional photographers to take pictures of actors smoking specific brands. …"

Not always. In the 1965 film Good Neighbor Sam, Jack Lemmon plays a San Francisco-based ad executive who has a Rainier Beer poster prominently displayed in his office even though Rainier Beer was sold only in the Pacific Northwest during the 60s. And then there’s Harold and Kumar Go to White Castle in which the titular fast-found place is a chain mostly limited to the Upper Midwest and the Northeast of the US.

My apologies for the mistake. The real question I have for the Superman movies is how much *The Daily Planet *paid for the free advertising.

Or how Lois Lane could afford that fantastic apartment on a reporter’s salary. The Planet must manage its finances really really well or really really badly.

…and didn’t mind admitting that most of their customers were stoned.