I don't know what u mean by primary purpose light colors but if you just asking for primary colors these are the only ones.
Keeping it simple means that the reason for your photograph is clear and understandable.
Answer: People rarely trust a new technology
Explanation:
They have not trusted this new technology because at first, it was a weird box with no light and people were using it to take pictures. That was scary to other people. Another problem was that those pictures who were taken at some point lost their colors and turned black so the others were not sure about this kind of new technology at first.