When I spoke to the Nursing Coordinator's of the ADN Course, at the college, they said that using the stethescope is learned manually for several reasons, one being if there were equipment failure, or if you are somewhere where there are no equipments, and etc.
They also mentioned that equipment used to take BP, is not always reliable, and accurate.
Heart, Lung, Bowels sounds and BP are required for the students to be certified in CNA and then move on to ADN.
That hasn't stopped me from going to CNA though.