ADA compliance will kill the entire thing. You can't charge someone for accommodation of a disability that prevents them from using the self checkout. All the human-staffed registers will be posted as handicap accessible, and they will default to the "discounted" self-checkout price.

when I recently went back to using a staffed lane, I told the folks I had anxiety about being in the lane, and the cashiers comforted me.

I have social anxiety, practicing in the staff lane, has helped me with this. At least, in this small area of life.

I get the point, but if a person doesnt ever push themselves, they wont grow.

Sure, I'm just saying, this wouldn't be a hard law to enforce.