In graphical, screen-based interfaces, all that the designer has available is control over perceived affordances. Most of this affordance is of no value. Thus, if the display does not have a touch-sensitive screen, the screen still affords touching, but it has no result on the computer system. But the affordance of touchability is the same in all cases. Touch sensitive screens often make their affordance visibly perceivable by displaying a cursor under the pointing spot.
Logical constraints use reasoning to determine the alternatives.
Cultural constraints are learned conventions that are shared by a cultural group. Once again, these cultural constraints are arbitrary. The scroll bar could have been designed very differently. It could have been located on the left, or the top, or as a button. Today if we were to use that convention, it would be confusing, but only because the convention has already been established.