And yet this family never picked it up...yes, more people do, particularly if they work in international business or tourism, but most people in most countries outside the Commonwealth and the Scandinavian countries do not speak English, apart from using a few anglicisms, particularly older ones.

But I was referring for example to refugees I know from countries where English is taught, and who have basic knowledge, but are not fluent, have trouble reading it, and so don't, etc. 

More than 15 years after arrival at the age of 30, their English has not improved, because of the reasons I stated, and the teenage kid born here struggles with reading because he has no vocabulary or basic cultural knowledge.