(05 Jan 2015, 12:37 pm)gneasy91 wrote during  the day just old people

Old people are charged, too.
Depending on how the bus company operates their system, this can be based on the maximum fare for the route.

Also, consider that without concessionary fares, many 'old people' would not use the buses as often.

I know that I use the bus to save money on what I would otherwise pay for milk by travelling to a cheaper supermarket.
If I had to pay to use the bus I wouldn't - I would just buy the more expensive milk.

On average I make three return journeys each week (not all for milk!) - none of which I would do if I had to pay for my tickets.