To my knowledge people generally are not saying that literally everyone has every implicit bias common in their societal groups. It’s saying that certain biases are particularly common among certain societal groups, and that it’s important to introspect your own life and consciousness to see which ones you have or don’t have. Each person has some subset of implicit biases determined by their experiences, their upbringing, and so on. The important thing about knowing and acknowledging that implicit biases are a thing is that it’s the first step towards understanding your own.

It is also important to realize that most humans are biased against admitting they’re wrong, and that it’s hard to see things you haven’t perceived before. So, it can be hard to recognize our own implicit biases without conscious and honest work. All anyone is saying is that doing that work can help to make everyone’s collective lives easier.