The phrase "careless people" refers to individuals who do not pay much attention to their actions or responsibilities. They may act without thinking about the consequences or take little consideration for others. Full definition
In reality, in my experience, you have to be pretty careless to get a virus, or else connected to an open network with a lot of careless people. (lawyerist.com)
We have the tools, experience and investigative resources needed to uncover gross negligence and hold careless people responsible for the deaths they cause. (m-s-lawyers.com)
Otherwise, you come across as careless and most employers don't want to hire careless people. (mashable.com)