Functional streets necessarily involve both cars and pedestrians. Because cars have become integral parts of our lives, we have many specialists with large budgets making sure that drivers can move to and from their daily activities. Yet these drivers eventually become pedestrians, an important but often overlooked component of functional streets. Witness also the long waiting times at crosslights.
Pedestrian safety is also critical.
The safer pedestrians feel on the street, the more they will use it. Being safe means not being in actual danger. Most streets in American towns have sufficient warnings and actual barriers between people and cars that accidents can be avoided. But feeling safe and comfortable on the street has to do with the perception of danger.