Why are people using products they don't know what the product does?

While we could answer what teatimer claims to do, let's tackle the bigger issue of the need for us to stop using products that don't share or document what they do?

While we know that TeaTimer "asks" if it's ok for some app or such to make registry changes if the owner didn't know what TeaTimer does, how would they know how to answer the question?
Bob