It needs to be very well publicised as many would not even consider the possibility of flying, or alternatively, consider it to be prohibitively expensive unless it's charters to the sun or FR to Europe.
Even in this day and age, in many peoples' minds, flying is still considered to be something only done a couple of times a year on holiday, and wouldn't consider flying to see friends/relatives in different parts of the UK.
Also suspect that many people are not even
aware that these possibilities exist.
It's a shame because it's always good to have a choice, and with increasing congestion on road and rail, the option of flying is becoming essential.