There are a lot of people who want to take their dogs everywhere, and so they sign up for "registration" websites and stuff so they can get vests and information cards.
For actual service dogs, no vests or harnesses are required. Just a legal disability and for the dog to provide tasks for a dog.
HOWEVER... also according to the laws, if a service dog is being unruly, businesses do have the right to refuse service, just like they would if a human was being unruly, without the service dog.
So... while service dogs that complete a task for an invisible disability are becoming more common as more and more people realize it's an option, I think there are also some people who see them without vests or certification and think "oh, I can take my dog here too!"... when that's not the case.
I am training my own service dog for when I have my recurrent episodes of major depression. 6-10 months out of the year I am fine and have no need for her. And then an episode hits. I have lost jobs because of it, my hygiene goes out the window, I have a lot of trouble completing even simple tasks such as making sure I take a shower at some point during a week, or get out of bed long enough to get food. My dog, when fully trained, is not expected to force me to do those things. I have to physically get up and do them. But having a dog that will pull me up if I ask, fetch medication and a bottle of water for me, ground me when I'm dissociating on top of the depression, and provide a tactile alarm when my other alarms go off, as well as other tasks... it's extremely helpful to me. What seems like an insurmountable obstacle now seems a bit easier because I have help.
But... my dog will very rarely be used for public access. Only during those episodes, and only if I'm likely to dissociate. Because while most of my dissociative episodes (which only happen during a depressive episode... hard to explain) happen when I'm alone due to the lack of activity around me... I have had them while in hotel rooms with my college equestrian team event and once during a class I was in.
I have support from my doctors.... but all this to say that while I have a disability that may support my need to have my dog with me at all times... I don't want to impose on people, so when she's fully trained, she will only be going with me to places if I feel like things are really bad... otherwise, she stays home, because with my illness, I really only need her at home.
So... I have read up on disability laws. Both the ADA and my state laws regarding service animals. And so many people haven't... and think it's "OK"... when they don't have a disability. But know enough to know that most stores are not allowed to even ask what your disability is. So they take their dogs with them into said places. Frustrating for those who need their dogs 24/7, and are denied access because of these people.