In the late 19th century, photographs were primarily made on huge plate-film cameras with bellows and expensive hand-ground lenses. Their operation was nontrivial, and required professional expertise.
The relative youth of photography as a medium made that expertise much more scarce than it is today. All that changed when Kodak introduced the Brownie Camera in 1900.
The Brownie was different. It was about as simple as cameras get: a cardboard box with a fixed-focus lens and a film spool at the back. It took 2 1/4 inch square photos on 117 roll film, which George Eastman had first used a decade earlier.
Millions of Brownies were sold through the 1960s. The simplicity of the camera made it reliable, and its low cost (around $25 in today's dollars) made it a low-risk purchase for families or even children.