because its like they are just selling puppies and kittens. they are everyday animals there isnt anything you need to really research about them since you grow up around them. so if you fall in love with a dog or cat you see someone selling at the booth and buy it there is no harm done. but if you replace the puppy and kittens with a sugar glider that is completely different. they are exotics the person most likly has no idea what they are getting into. gliders need a cage, the right diet, pouches, toys, a vet, and so on. how many people seeing a glider at a booth will have all of that set up for the glider they just saw at a booth. lots of research should done before buying them. thats how so many gliders end up for rehomeing or in rescues. its always best to adopt or buy from a breeder that you have talked to and know they are someone who cares about gliders.
i hope that made sense not feeling too well at the moment.