Why do bees pollenate the earth?

Bees don't wake up in the morning and think 'I must go and pollinate some flowers today.' They visit the flowers for one purpose only: to get food. They live on nectar and pollen, both of which they get from flowers. In going from flower to flower to collect food they just happen to transfer some pollen from one flower to the next. The flowers give the nectar in order to encourage the bees to visit.