Whys is asterisk and random variable necessary in these functions?

[DeaD_EyE]

The function signature is misleading. Don't use the asterisk, if you expect a static number of arguments. The callback sends one argument, which is the event itself. You should change the callbacks (example taken form Gribouillis).

# Change text with "Enter" then flush
def changeTextEnter(event):
    print('changeTextEnter:', event)
    text_label.configure(text=entry_bar.get())
    entry_bar.delete(0, tk.END)
  
# Close program key function
def quitApp(event):
    print('quit:', event)
    main_window.destroy()