As a hiring manager, it's been helpful for me to be thoughtful about asking things like, "how did you get here, car, train?" - as this implies socioeconomic status, and if you reflect on why you asked that, what you wanted to know about it, and how it affected your thinking in general, and were honest, there's a chance it might have affected your opinion of the person in a way that has nothing to do with their ability to do the job. This opinion could be either good or bad, and isn't necessarily dependent on whether the person you're interviewing is from a marginalized class.
I still have bias, everyone does, these trainings do not aim to eliminate bias, they aim to inform people that it exists, and to offer them tools to be thoughtful about those biases, and to challenge folks to question the biases that potentially harm others, even if unintentionally.