I have a great difficulty with French. This is despite the fact I was raised surrounded by the French culture and studied the language as part of my school curriculum for 16 years - leading to my final exams written in French. This would be the period of pre-kindergarden to high school matriculation.
I often see these "innocent questions" on the forums. They upset me because, more often not, they are a big excuse for someone to carry over the fundamental attribution error and judge people. I am not saying that is the intention but I would like to clarify a few things. [Sorry if I am repeating arguments written before - I would be happy if they were better known - but I cannot read through the whole topic with the time I have at present. ]
If you think hearing Polish people say "You have live here [so long] so you must speak Polish fluently" is insulting, try this: "You don't speak French, you? For me it is the same thing, of course. If it is not obvious, I have a learning disability. Or I am an incredibly stupid person to be able to learn something as useful as the language of my host (French, Polish, whatever) but refuse to. Just because I have a learning disability does not mean I am stupid.
Next thing is that English is the predominent language in the world. If you know the history of the language, you would be correct to think of it as successful Esperanto type. More people speak Chinese, obviously, but that really is not as useful as the statistic makes it seem outside of China or Chinatown. Some who make criticism a blood sport try to "catch me" with the logic that I should unable to speak English if I have cannot speak French.
French would be a much better comparison language to English than Polish, especially in my case. In my case, because I am foreign to the Polish language and its culture and have not studied it as a pass/fail requirement of my schooling.
French is also used within the structure of English, as are vocabulary elements of many other languages since it is the language of an Empire not merely a nation.
I am also subject to ghettoization (a word itself stolen from Italian) from the locals who wish me to speak English. While in my case this is a blessing, it can also be a root cause for non-Poles not speaking the Polish language. And since English is the predominent language of the world, I certainly understand the reason why Poles wish to speak it.
I am very grateful to speak it as well as I do (i.e. my family and friends spoke it well).
These are a few objective reasons why anyone may not speak a foreign language. IMHO, they should be considered by everyone who asks these "innocent questions."
Just to make a point here - the vast majority of fluent speakers don't need to be taught English! Why would you teach a fluent person a language, unless it was ESP?
LIVING CONTACT with the language is important to keep the language.
I have lived in Poland an extended period of time and, though a native English speaker, my English has suffered tremendously. I used to be proud of my level of English being greater than other natives - actually recorded through testing as an adult. Presently I practice my English using role playing games with other expats so as not to lose my English facility.
I am a native English speaker.