it's because this, like the ATF's program "Fast and the Furious," is an underhanded play to disarm Americans and deny them of their 2nd Amendment rights through extralegal means. It's mentioned right in TFA!
>From 2006-2011 [federal] agents in Arizona stood down as straw purchasers illegally bought 2,000 guns at shops, intending to use the information to track trafficking patterns and arrest the kingpins. However, agents didn’t deliver the high-level arrests – and in the process, they lost track of hundreds of guns.
>Hundreds of Fast and Furious firearms have previously been traced to other shootings in Mexico. The new leak indicates hundreds more are still being found.
US government sells guns to cartels to prove that guns are being sold to cartels, then sues manufacturers. And people wonder why the country has lost faith in its leaders.