Can you explain this with links to the laws?

In a normal country the vast majority of these 'foreigners' would long since be citizens.

I wonder how many normal countries Europe might have? How do you become a citizen of Great Britain, France, Sweden, Norway, Switzerland, Austria, Italy, Spain and Portugal, if you are a foreigner? If you are a citizen of the EU, are you still considered a foreigner, if you switch countries within the EU for work and residency? In how far is it different when you are a "Chinese foreigner" in Germany versus an "Italian foreigner" or a "Rumanian foreigner"?

Are there really European countries that have laws like the US, whereby you can become a citizen after having been a permanent resident with permission to work in the US for seven years? I don't know about Canada, but isn't the difference that most European countries don't have the equivalent of a green card, i.e. an unconditional permission to work and reside in the country for an unlimited time?

And how can you strip someone of his citizenship, once you had it? Wouldn't that person become "Staatenlos" (a person without a nationality)?