Some years ago I was visiting Germany for the first time, and while walking the city I passed an area with 20+ police vans and dozens of officers armed with assault rifles.

I paused and politely asked one of the cops if there was something going on... or why was there such heavily armed police presence? He casually said, "oh there's a football match here this afternoon".

I suspect it's something to do with association football itself.

I believe baseball is traditionally a working-class entertainment; but the fans will clap and cheer the opposing team. NFL football is a chance for everyone to get together and eat hotdogs. People go to matches where they don't support either team.

Football/soccer fans only go to matches where their team is playing. There are two matches - one on the field, and one between the fans (which crowd can sing or shout loudest). Certainly, the crowd at UK football matches is much louder and more excited than the crowd at baseball and NFL matches (omitting superbowl).

I don't know anything about college football.

A bit of nitpick but I’ve never seen German police with assault rifles (unlike the US, France, and Belgium). There were more likely MP5 machine pistols which are quite commonly carried in sensitive areas or around major events as a “show of force”.

Hooligans can be bad, but they are not gunshot-bad. Riot gear typically suffices. And most hooligan action is anyways happening outside the stadiums nowadays.

Generally, I assume the public thinks that anything physically bigger than a pistol and smaller than a rifle is an "assault rifle".

If you wanted, you could own an MP5 that would be categorized as an assault rifle, to do so you would need to make it LESS lethal, by converting it from a fully automatic weapon into a semi-automatic, and would need to put a longer barrel on it. Such versions are sold in the US.

"Assault Rifle" is very much an actual term for an actual classification of military firearm, and is a literal translation of the German term to English from the original assault rifle, the Sturmgewehr 44 created by the Germans during WW2. Moreover, the reason an MP5 is called an MP5, is that the MP stands for Maschinenpistole which literally translates to "machine pistol", and is the next closest type of weapon in German parlance to an assault rifle. In fact, the StG 44 derived from the MP44, which fired a smaller cartridge.

Mechanically, both assault rifles and machine pistols operate similarly, the primary difference is the cartridge. Assault rifles fire intermediate rifle cartridges (smaller than a battle rifle cartridge) [e.g. 5.56 NATO (.223 Remington)], and machine pistols fire pistol cartridges [e.g. 9MM NATO]. Machine pistols in the US are classified as sub-machine guns. The history of that is equally interesting, but irrelevant to this sub-thread.

There are no civilian owned Assault Rifles manufactured after 1986 in the US, except when held by a Class 3 FFL (federally licenses firearms dealer), or purchased by a police department or specially licenses corporate security organizations (think PMCs). They are considered to be exclusively military weapons that do not pass the "sporting purpose" test enacted in the Firearm Owner's Protection Act of 1986 (ironically named, since it didn't do anything of the sort). This is especially ironic because the entire reason shortened barrel shotguns being illegal in the National Firearms Act of 1934 was upheld in the US Supreme Court (Miller v United States) is due to it not having a military purpose, the purpose of the 2nd Amendment being that US citizens have an innate right to possess, train with, and utilize military equivalent arms. So taken together, in the US a firearm must have a "sporting purpose" and also be military equivalent in order to be legal... luckily that contradiction does not completely eliminate most firearms.

That being said, I have no idea about how they police football games, so you may well be right!

It might help that most beer sold in US stadiums tends to be mass produced beer with low alcohol content (Coors Light is only %4.2). Still, it's nice to have something that's not a heavy beer in the summer.

I think it’s mostly an issue with the "Ultras", but as a non-fan I don’t know much about it.

I think there's a different cultural attitude towards fighting here. Fighting with fists is something boys do that they grow out of. Of course American culture has a macho aspect that see violence as a fundamental masculine skill, but even people who buy heavily into it don't have an idea of fighting as good clean fun. Fights where nobody gets really hurt are kid stuff, because men should be more capable than that. Serious violence will likely involve guns, which only makes sense for extremely desperate people and/or criminals, so if you're not a hardened criminal, living in wretched poverty, or a failed man-child, you look silly initiating physical violence. Though of course you watch it constantly on TV and in movies and constantly worry about your (assured in-)ability to turn into a bad-ass on a moment's notice if necessary, because it's fully expected of you.

And of course popular culture is incredibly nostalgic for the days of casual fighting in bars, because it's exciting entertainment and a great way to build characters that people want to identify with.

In NA it's typically all home team crowd, either you're all happy together celebrating the win or all sad together mourning a loss.

Always. For most teams and countries basically all your away games are less than an 8 hour drive/train ride away (and in many cases less than 2-3 hours) so many people make the trip. You also always have the hardcore fans that will rent a bus or two and drive it literally across Europe to see their team play.

Did you really ask them? Riot police usually don't go out of their way to casually interact with members of the public.