I think this isn't a technical problem. Ebay has the same challenge, and similar solution (Ebay uses dropdowns, while Amazon uses small clickable boxes), but I

I think this isn't a technical problem. Ebay has the same challenge, and similar solution (Ebay uses dropdowns, while Amazon uses small clickable boxes), but I see the problem much less on Ebay, so I think Ebay is simply policing sales more than Amazon does.