During certain hours of the day, billboards can only display ads from companies that have earned exposure through good deeds.
Reward good deeds.
Encourage an altruistic culture.
Companies receive support from people for good reasons rather than mindless spam.
Society benefits from all the good deeds that are performed by entities that want billboard exposure.
During certain times of the day, require that all billboards display only advertisements for companies that have earned exposure by doing good deeds. All billboards have to be digital and connected to a city-controlled system.
Come up with a rule-set and a way to place a measurable value on good deeds. It should:
Even the playing field for entities that have a lot of money versus those that don't
Prefer work to investment. Consider the size of the team.
Prevent cheating/tricks by investigating all reports of foul play.
Entities that wish to advertise on billboards during "good deed hours" pay for the time/exposure with their earned karma.
Centrally controlled advertisement of billboards
Any billboard owner has to install a centrally controlled system that pauses the regular program and puts on the "good deeds" program during certain hours. Operating billboards without this system shouldn't be allowed.
Cons to centrally controlled advertisement:
Someone could hack all billboards and do maximum damage. On the other hand, what damage could be done by information that humanity is not already used to?
Opens the door to future censorship. On the other hand, this has already been happening for decades.
Opens the door for centrally controlled manipulation. On the other hand, this has already been happening with mainstream media ever since the press was invented.
The above idea is an attempt to upgrade this one and make it more feasible. If all advertisers run out of karma, just play cute animal videos and encouraging messages as the linked idea suggests:)