They assume that pets at the animal shelter will be difficult to train
Potential pet owners who would prefer to work with a breeder or head to the pet store often think that a pet from the animal shelter will be difficult to train.
Many animal shelters have a couple of animals who were neglected or abused by their previous owners, and those animals may have a few behavioral issues (or they may not). Every pet needs proper training, and fortunately, the process likely won’t prove any harder with a shelter pet.