THE POLICE PROBLEM

You're emphasizing the wrong part, imo. The overall societal negligence of mental health, especially for young males, is the biggest 'fish to fry'. By that I mean the ratio of reduction in gun crime to amount of resources put in is best in addressing that issue head-on, and I feel said issue needs to get a LOT better before that will stop being the case.

After all, what's better: preventing a homicidal person from getting access to a gun, or preventing a person from becoming homicidal in the first place?

I even wonder if no guns at all would somehow decrease public shootings, are there any countries that implement that policy?

I'm in the U.S. The problem is that violence is almost literally the cornerstone of our culture. The entire prehistory and history of the U.S. starts with violence. Displacing a people, warring with them for centuries to carve out a place in a land that keeps killing settlers. More violence and death as cities are established and more natives are killed. Every other super power at the time killing each other over this land, finally the descendents of the settlers revolting against foreign rule, more war, and a country established on stolen, blood soaked land. Built, fed, and clothed by slaves.

All the whole fighting neighboring descendents of settlers in bloody wars, over stolen land, driven unceasingly by "Manifest Destiny".

More war as the descendents of settlers, now natives to their barely 100 year old country, proceed to kill each other over the right to enslave others, creating a cultural schism that still exists over 150 years later.

Fast forward through two global wars barely 50 years later, and hardly a generation apart, we have global Mutual Assured Destruction doctrine casting a shadow over every single human life for every day since 1962.

An oft forgotten underground sea of violence lies between the fragile crust of civility that supports U.S. society. Even the government itself is adversarial, pitting branch against branch, state against federal, local against state to maintain a balance checked by the threat of violence and anarchy.

Oh, and through it all, an ever present an undercurrent of racism, a miasma permeating the fabric of everything this country was built on and with.

Historically, when it wasn't guns, it was mobs, lynching, firebombing entire towns and neighborhoods, knives, fists, terrorism, crosses set on fire, sundown towns, racist rallies, segregation, cultural warfare, propaganda, economic terrorism and oppression through targeted laws, the prison system, low wages, and the violence inherent in capitalism in general.

Violence has driven, and continues to drive, the vast majority of decisions made in this country.

tl;dr analogy: The guns are the polar bear sitting on the melting iceberg. The violence inherent in U.S. culture is the ever rising global average temperature, and we're not even pretending to address the violence.

Americans always try to make this complicated

Not all of us do though, just enough people are rabid about doing so that we can barely ever make an ounce of progress. It is pretty fucking obvious that millions of guns easily available are the problem. You have to work pretty hard to think otherwise. When Tylenol killed kids overdosing, no one started looking for ways to argue against fixing that issue, we just started looking for ways to reduce kids' access to it because it was a no brainer.