Question of the week: Why are so many drivers reluctant to use bus lanes?

Dear Honest John,
"Why are motorists so afraid to use bus lanes when they can legally? The Highway Code is quite specific about returning to the left side of the road when it is safe to do so."
- AM
Dear AM,
You may be pleased to know this is something I often find myself wondering. Bus lanes are a sometimes controversial topic, but they are designed to encourage the use of public transport over private cars and being passed by a bus while sitting in traffic suggests they have some value.
However, an observant driver will make use of all the available lanes and obey Rule 264 of the Highway Code which states you should keep left unless overtaking.
It may be that many drivers are too lazy or inattentive to notice the signs displaying a bus lane's times of operation. Or potentially that the fear of fines for driving in a bus lane discourage them from doing so. On the other hand, while some drivers are reluctant to use them it leaves them clear for good drivers to take advantage of.
I live very close to a bus lane that is in operation from 7am until 7pm Monday to Saturday with no hours of operation on Sundays and frequently find myself the only non-taxi making use of a clear left lane while traffic queues pointlessly on the right.
I even received a PCN for allegedly driving illegally in the bus lane while it was in operation and duly found that in the provided evidence the authorities' own video timestamp proved that the lane was not in operation at the time. Rest assured I was quick to respond that to not drive in the left lane at the time would have broken Rule 264 of the Highway Code. Needless to say, the PCN was overturned.
What are the time limits for a PCN?
