For most of its life, all Kodachrome sold in Canada included processing in its price. Kodak included a convenience envelope in the package, but it was the film cassette itself that confirmed that the processing was pre-paid.
In the US, Kodak was prohibited from selling the film including processing as a result of a consent decree issued in an anti-trust case initiated by the US government.
Yea, the US government is dumb... at least with that... I would venture a guess that if process payed film were still allowed, film would have gone on a bit longer, and Kodachrome might have been around a few more years as well. The convenience of not leaving your house for things is not to be laughed at...
~Stone | "...of course, that's just my opinion. I could be wrong."~Dennis Miller