Setting aside for a moment that such a ban would be unconstitutional, and that it's far from certain that it would reduce violent crime, and that it could actually cause a greater number of people to be killed because they'd be less able to repel an attacker...setting aside all those things, let's just consider the enforcement of such a ban.
America has a long and unsuccessful history of banning things and then having those bans skirted. When the American colonies were still under British rule, and the Crown imposed too many taxes on the colonists, the colonists simply stopped paying. During the Revolution, even though desertion carried a death sentence, soldiers still deserted anyway, to the point that General Washington started having deserters executed by their own best friends. After the Revolution was fought and Congress disbanded the new country's military forces, they kept a few Navy ships in service to catch smugglers, because there were a significant number of merchants willing to sneak goods into the country illegally rather than obeying the law and paying the required taxes.
In the 1920s, in response to a nationwide epidemic of alcoholism, Congress passed the 18th Amendment, which banned alcohol. That ban lasted just shy of 15 years. The battles between police and alcohol traffickers, not to mention the battles between the criminals themselves, cost countless lives. By some reports, alcohol became even more available during Prohibition because there was no regulation of production or distribution, and the profit motive was greater. In 1971, President Nixon declared a War on Drugs. Forty-six years later, we're still at it. The drugs are still there, people's lives are ruined as much by overzealous enforcement as by the drugs themselves, and nobody's benefiting but the private prison industry. Forty-six years later, the drugs aren't gone, and the states, one by one, are starting to decriminalize drugs in defiance of federal law.
My point here is that Americans have a long history of looking at legal prohibitions as being "helpful suggestions" more than absolute moral codes. The very founding of our nation was a defiance of the law.
This is important to keep in mind when envisioning what enforcement of a gun ban in the United States would actually look like. Given that many gun owners see their guns as quasi-religious talismans representing liberty itself, and that even less idealistic gun owners often see their guns as necessary, lifesaving, safety equipment, many say they would fire on anyone who tried to seize their guns. G. Gordon Liddy infamously advised his radio audience that when the ATF showed up to seize their guns, "Just remember, they’re wearing flak jackets and you’re better off shooting for the head.”
As with firearms, many Americans also have a patriotic, sentimental attachment to fireworks, which they set off in celebration of Independence Day on the 4th of July each year. Unlike guns, nobody sees these fireworks as being necessary for self-preservation. Nobody is relying on fireworks to protect their family from criminals. Nobody's counting on fireworks for protection against a violent ex-spouse. They aren't stockpiling fireworks to fend off invading armies or government tyranny. It's just for fun.
Fireworks regulations vary from state to state. In Ohio, adults are allowed to possess sparklers, smoke devices, and "bang snaps"--tiny noisemakers that explode when thrown against a hard surface. But the state bans residents from purchasing firecrackers, Roman candles, bottle rockets, and fountains without signing an affidavit promising to transport them out of the state within 48 hours. It requires any Ohioan possessing aerial burst fireworks to be a licensed pyrotechnician. The Ohio State Fire Marshall's Office says it seizes about 15,000 pounds of illegal fireworks annually. Violations--including falsifying paperwork, illegal possession, and exploding fireworks in-state--are usually 1st degree misdemeanors, carrying a punishment of up to six months in jail and a $1,000 fine for a first offense. With all of this in mind, listen to this video I recorded in my back yard in Columbus, Ohio, on the Fourth of July this year. Neighbors in every direction were shooting off not just firecrackers and bottle rockets, but professional aerial display fireworks. (You'll get a few, brief glimpses of these in the video, but otherwise it's all dark. Just listen to the sounds.) Each pop you hear is a violation of the law that could get a person locked up for six months. Turn up the sound and have a listen to how much people care about the threat of fines and imprisonment getting in their way of having a good time celebrating their nation's founding.
Despite the ease of tracking down who's making giant explosions over their back yards, police make little attempt to enforce the fireworks ban simply because non-compliance is overwhelming. If they actually attempted to arrest every illegal fireworks possessor, they'd be doing nothing else but that, and they'd still fail to catch all violators.
If Americans will willfully defy the law on this scale to obtain and very conspicuously explode illegal fireworks just for fun, imagine how much greater the defiance would be to possess something they see as protecting their lives and ensuring all their other rights.
So that's one reason we don't ban guns here. There just wouldn't be any point. We'd have to create a massive, new law enforcement agency with incredible powers to do unannounced, door-to-door searches just to make a dent in the number of privately possessed firearms. And a lot of the gun owners would shoot back. It's estimated that there are more than 300 million guns in America. How many law enforcement officers would it take to seize them all by force? We would essentially need to employ an army to invade and occupy our communities. We would be turning our own homeland into Iraq, with troops fighting door to door in our streets. Millions would die, forcing us to reconsider what the point of banning guns was in the first place.