Interaction compromises everything that a user can somehow change and receive feedbacks from a product or interface. A field that I have much dwelled is the point of usability of interfaces, analog or digital, for end users.
I am of the firm belief that there is no reason whatsoever that technology should be difficult to use. In the past there was necessity that if someone wanted to operate a machine they had to go through courses and certificates. Today children are growing with technology that their parents could only imagine in sci-fi movies. The children understand it. The parents do not.
The responsibility to make it easy for the user to operate/interact with any object/technology lies most of the time on the lap of engineers that know too well how a particular system works. To blame the user for not having the ability to operate any kind of technology because of its complexity it is not a valid reason anymore.