Even the legally blind know how to operate a checkout register. But for some reason most machines are radical redesigns that actively work against a lifetime of expectations. 'Juggle these dozen items between three locations while comprehensively reading arbitrary instructions' is absolutely asking a lot of people, especially if you want it done correctly and quickly.

That's before including hesitance where people have been betrayed. Even 'Pay now?' is reason to think, As opposed to what?, and take a second to look around the interface, because Oops, go back one step might summon an employee and lock you out.

In the Netherlands , 18% of the population can’t properly read (functioneel analfabeet).

Yeah I didn’t believe that either first time I read that.

Working with office and business types all day long in a highly technical field, I will say this: people don't even bother reading when it's literally their job to read, understand and act upon something.

I'm not even going to touch the minimum of reasoning thing.