Color me Naieve, but when did Apple charge software developers in the 80's and 90's for Mac development?
From the very beginning.
When the Mac first came out, you had to buy a Lisa and Lisa Workshop to do Mac development.
Then MPW came out a few years later, and you no longer had to buy a Lisa.. but MPW was *not* free until after XCode came out.
Basically, until XCode, it costs thousands of dollars to develop for the macintosh.