Some companies offer a bonus for not being involved in an accident/claim over the year.
There are others for driving in a fuel efficient manner.
Maybe your idea needs putting into play! Just hope the drivers stop and pick passengers up in their rush to be on time!

As for the discounts, suppose different companies have their own reasons. Competition will be a factor - GNE, SNE, ANE, Nexus and Network Traveltickets all need custom.
However, if these companies can make money on a discounted product - it maybe shows the profit/mark up being made on a full price product.