The push for the home market was started in the 60s and they were getting more common during the 70s, and of course the 1980s.
“Sales volume of 40,000 units for the U.S. industry in 1970 grew to one million by 1975.” “By 1972, Litton (Litton Atherton Division, Minneapolis) introduced two new microwave ovens, priced at $349 and $399, to tap into the market estimated at $750 million by 1976”
Ya. I was in -again- the New York suburbs as a baby boomer
No one was coming home from school to an empty house microwaving anything
That’s all