"The government could buy as many as possible and destroy them (since they are so cheap) "
They would just make even larger quantities.
" Track who sells them and US buyers, build an address list. International shipments can be inspected. Watch for the heavy US users. Track behavior and and send a few letters of their own. Really wouldn't be that difficult."
You make it sound so easy. The only way to get any buyer and seller info from
ebay is with their cooperation, which isn't forthcoming, and many of the sellers are probably giving
ebay fake addresses. Getting any info at all from social media platforms would be even more difficult.