How much public money is being lost by bus scam?

• I AM getting annoyed at the number of “free” passengers travelling on buses.
I witness these frequently and regret to say they are encouraged by employees of London Buses themselves, the drivers who are expected to issue and check tickets.
The scam involves  the passenger pleading poverty to the driver who is apparently only too willing to accept any excuse, unwilling to involve him or herself  in  any possible confrontation.
How often does this occur?
How much public money is being lost?
Are London Buses aware of these practices being encouraged by their own employees?
This practice is most widespread later in the evening when few inspectors are available to check tickets.
I WALKER
Dalgarno Gardens, W10