been in Sweden for 30 years still do not know Swedish!!

I just saw an interview with a woman from Libya, she and her husband came to Sweden for over more than 30 years ago.
Sadly the woman couldn't speak almost any Swedish at all.
I have to ask.. how come? The couple came to Sweden such a long time ago? And back then I guess a fewer people spoke English compare to today.

Also.. how can somebody live in a country for such a long time without learning the language?
Her English was fine, still our native language is Swedish.
And in my view, after 30 years you should be able to speak the language.
I've met people who have only lived in Sweden for 1 year and they can speak well!!
I do know Swedish is difficult, it's not about 100% perfection however to be able to understand and be able to make yourself understood in the country you live in, isn't that important?

There are many places to go and learn the language!!Also you live in the country and can hear and practise it much easier!!
I guess it's all about will and wish!!