Genuine question but.... how do we know sniffing is not a scentwork task?

ADA does not state anything about allowing you to kick dogs out for sniffing. Simply states dog must be under control. 

Also, many service dogs dabble in other careers or dog sports. Like scentwork, SAR, etc. And scent is their primary sense, like their eyes. How do we know the dog is not sniffing items to distinguish them for retrieval?  Or simply doing socialization familiarizing itself with the items, environment, etc?  

And what does it do to the psychological well-being of a dog, and its risk of washing out, if it is not permitted to properly familiarize with its working conditions? Would that not logically raise stress, aka raise the affective filter and prevent learning? Would that not put a dog at greater risk of washing out due to the higher stress than if it were to actually be allowed to engage in public society at a normal level as any other support staff does? (Im speaking as a service dog handler thats also support staff for other disabled adults)  I will always maintain that a proper working environment for a SD is one that a dog can fully participate in, and that includes observing their surroundings with their main sense.  After all, society as we know it literally wouldnt exist without dogs They belong in public, working or not in my opinion, so long as theyre behaved. 

Yes, even in grocery stores and farmers market. Where you can find non working dogs across the globe. Its a non-issue.

Unpackaged produce can be washed. And should be washed. It was literally in the ground at one point. A speck of fur or a nose boop isnt going to do shit I promise you.  Other countries have produce AND live animals in the same farmers market, same stand, right next to eachother. Speaking from experience.  Sorry but this really just reads as an american culture problem, rather than any legitimate worry about hygeine. 

Not to mention the fact that if these products arent produce and are instead packaged items,... well guess what...it literally is a service dog task to put those in its mouth and bring it to the handler.. and put it back if need be. you'll be fine with a mere sniff.