There is unused spectrum in these bands mainly because of the necessary geographical separation between television stations of the same channel, as well as parts of the spectrum dedicated to regional television stations that remain unused in certain areas.
Some internet players are advocating globally for use of TV white space for licence-exempt services such as Wi-Fi. It is worth noting that commercially desirable geographic areas such as major urban and suburban areas with high population and business densities typically have little, if any, TV white space at all.