I don’t know what kind of drugs might be involved, but prescription-type drugs would not surprise me.
“...prescription-type drugs would not surprise me...”
If the “prescription-type drugs” in fact had been prescribed to the driver herself, and if the driver took exactly the dosage she was supposed to, then I, too, would not be surprised if “prescription-type drugs” were involved. What I doubt is that this driver has been taking a daily normal dosage of, say, Prozac.