That is absolutely false.  They set standards to ensure that animals are properly cared for.  Zoos depend on animal loans.  Most animals at our zoo actually belong to other zoos under the AZA accreditation.  Without such certification there is no assurance animals will be properly cared for.  They are still not really sure what caused the hippo to die.  They just said stress.  I worked there for three years and quit because the place is such a mess.  There is no real incentive to change.