That said, US is a collection of regions with very different social setups and it is easy to move between them. It is common, as preferences change, for youngsters to live for a few years in one state, settle to raise children in another, then move as empty-nesters to third.
If safety is what one is after, one can find a place that is super safe, comparable on safety to anywhere in the world. Someone else would aim for nightlife instead. This flexibility is what makes US very livable for me. Just my 2c.
But I've got to admit that Maine looks pretty safe according to https://www.gunviolencearchive.org/charts-and-maps
Also, it sounds strange to me to look at guns as an inverse proxy for safety. I would, especially with kids, first look at drug prevalence and second at accidents on the roads (both cars and bikes). Which reinforces what I started with: the ability to select the place I want to live in based on my own preferences. Given a wide variety of options, both politically and socially, one can usually find a place they are happy in. My 2c.
The only barrier to buying a flat or house might be slightly reduced access to loans. I found in Denmark it is easier for a Dane to get a loan for 95% of the house value, but foreigners might only get 80%. EU citizens are somewhere in the middle, depending what the banks think.
Language is the main problem. If you aren't fluent in the new country's language, you can have problems with government bureaucracy, school/work, socialising, children's lives, doctors etc. If you speak English these are much reduced in countries with high English proficiency (IS/NO/SE/FI/DK/NL/LU/CY, obviously IE/MT). Or, if you are moving where there's already a significant community of people speaking your language.
Do kids from other countries tend to be accepted well in schools? I heard that at least in France schools can be very clique-ish and coming from the outside the kid can face significant hurdles. But I am just parroting what I heard elsewhere.
Not knowing/learning the language also works for some jobs like cleaning or agriculture, if so many workers are migrants that everyone speaks Romanian or English etc. Also postgraduate students.
Plenty of people from the north who move south when they retire (e.g. Netherlands to Spain, Germany to Greece) move before learning the language.
How quickly people learn the local language depends. Slowly in Denmark or the Netherlands where English is almost universal and work is often done in English, quickly in France or Italy where the opposite applies. Slowly if you're 65 and surrounded by other Dutch pensioners.
From what I know of France, a child from the other side of France can also be excluded, but this is from French emigrants teasing each other. I haven't heard of similar problems in Denmark.
Growing up in London I didn't even notice the European immigrants in my class and could hardly exclude the 40% of the class who were descendents of South Asian immigrants, but this varies significantly around the country.
I expect compared to the USA there's much more reluctance to move when a child is 14-18 years old, unless they can be certain of a place in the French school in Copenhagen etc. But this is primarily because of the difference in exams and language.
Some of us have family and friends here or simply can’t afford to live in the EU if we wanted to.
I do sympathize though. I do not have kids (yet) but our move from TN > Maine is definitely partially motivated by the fact that I said I would absolutely never raise a child in the south due to gun culture and archaic legislation in general. For example most states in the south still allow school teachers and administrators to hit children- most of this happens in Mississippi and TN, then basically other states where lots of poverty, christianity, or mormonism are.
Idk, there are many cities outside the US where I wouldn't want to stay more than absolutely necessary, let alone raise children.