a freerider on the beneficial actions of others

For example, if each of us pollutes less by paying a bit extra for our cars, we all benefit from the reduction of harmful gases in the air we breathe and even in the reduced harm to the ozone layer that protects us against exposure to carcinogenic ultraviolet radiation…

Unfortunately, my polluting less does not matter enough for anyone — especially me — to notice. Therefore, I may not contribute my share toward not fouling the atmosphere. I may be a freerider on the beneficial actions of others. – the freerider problem