Bats that pollinate plants want lots of sugary nectar. The plants they visit give them limited quantities of watery nectars: 20% sugar content versus the 60% preferred.
The ultimate reason is an overabundance of bats. There is a fierce competition for a limited amount of nectar.
The proximate cause is bats’ own preference in trade-off. A bat prefers more nectar even if it is less sugary, so that is what plants deliver. And, following the inexorable law of show business, a plant leaves them wanting for more. Thus pollination proceeds.
Multiple dimensions can interact and cause nonrational decisions, where you are given 2 options and you actually take the lesser one. ~ American neurobiologist York Winter