Traditions allow groups of people to express themselves in ways that aren't just words. The wai is a polite form of greeting that shows your kindness to others. Being considerate of your head and feet also does the same thing. Showing respect for the people in your community shows that you are a part of the same tribe. Traditions are a language that reveals a person's connection to places, things or people.
Thailand is a culture that believes in community first over being an individual. The people here have their shared beliefs and ways of living that they have passed down for generations. The wai, polite words and rules about heads and feet reflect ideas about respect that people practice in everyday life to bind themselves to one another. Also, taking your shoes off at the door is just the most effective way to keep things clean, haha!