Why are the front doors of European homes stronger than USA ?

Frankly speaking, in Europe like in UK, people paid close attention to the home security. UK Standard 3621 is the level required by British insurance companies on all wooden doors.

In UK, doors fitted with multi-point locking mechanisms because the industry is leaving the insurers behind on that one, but for the most part, they are ahead of the mighty EU standards who are in turn, ahead of the USA.

The standard locks in the US appear to be extremely easy to bypass for someone who knows what they are doing. But, let's be honest, to the outside world, it looks like everyone and his dog owns a gun in America, and 70% of gun owners appear to be about as intelligent as a used lavatory brush. So why bother with decent locks when any idiot can get hold of a gun capable of shredding your door to pieces? Just from talking to gun owners on this site, I get the impression US citizens expect intruders to get through their door and for the expected gun fight to actually happen inside their home.

In places where gun ownership is not so common, we look for ways to deter the intruder from coming to our home by making our security better than our neighbours' security. An unarmed burglar wants the easy break in. An armed burglar might just fancy his down weapon will work better than the hoe occupier scrabbling to pick up, aim and shoot theirs.

So maybe it's a mentality thing. Americans in general don't put much emphasis on home security because they have guns.

And for the sake of keeping everything even, I also understand outside of the concrete cities, American houses are often wood construction whereas across Europe we have built things from stone for centuries. May not be worth putting a better lock on a property built of wood.