"Then, hours later a dude comes in and buys a gun, you're supposed to sit there and stare at every person that buys a gun and think,..."
Frank made the point a couple of times that these cases depends on the specific facts, which we don't have for this case.
Ryanxia's comment is an example - he's implicitly assuming a set of facts - a busy store, nothing memorable about the customer, etc. That's one of the possible sets of facts, and a set that would argue against liability.
But there are other possible sets of facts. Suppose Alice and Bob visit the store. Alice picks out a gun, while Bob is uninterested - he spends the whole time playing Angry Birds in a corner of the store. When Alice is filling out the 4473 she asks about the 'No convictions' part: "What's this? Are you saying I can't buy a gun because of a bull**** 20 year old 2nd degree murder conviction for killing a dude who totally deserved it?". The clerk says, sorry, that's what it means. She leaves in a huff.
Hours later Bob comes back. It was a slow day, and the clerk instantly recognizes him. Bob says 'Uh, yeah, I decided I want to buy a ...(pulls out a note) 'Glack? Glock? something like that, in ...uh ... 9 caliber'.
Now, I don't think straw purchase laws actually do much good. Even if the clerk sends Bob packing, Bob and Alice have learned, and they'll just visit another store with a more polished act. But I also think that, with those facts, a reasonably prudent clerk ought to refuse to sell to Bob, and if a reckless clerk sells anyway, the clerk can't escape liability. This isn't a gun specific thing; if you loan your car to your obviously blind drunk friend, you should be liable.
It's important to not assume one or another set of facts, and then extrapolate a conclusion to the general case.
