We allow gas stations to have diesel pumps right next to gasoline ones. We just require that they be labeled appropriately and its expected that people read the label and not make assumptions based off proximity.
OTC medical matter isn’t regulated anywhere as tightly as active drugs. They’re supplements or food additives or other such things. Whole lot of that shelf space goes to stuff that’s not as useful or desirable as people think. And any ambiguity is naturally exploited to the max.
Nearly every market where the quality or efficacy of the product isn't readily verifiable by the purchaser is a hotbed for scams and snake oil.
Also, even in America I think you can order contacts and glasses online without a prescription; you just have to know your numbers.
Here in Japan, you do not need a prescription to buy contacts; you can just write down your numbers on a form and buy them over-the-counter.