When did this happen?
It’s been true for many, many decades. People don’t realize it because
(1) The testing was so bad: Prior to the closing years of the Bush administration, anyone only had to memorize, “A B A D C B A,” etc., to pass, since the same test was administered to everyone and was publicly available.
(2) People figure that if you’re naturalized then you came here legally, forgetting that we’ve given several amnesties to a total of almost 10 million previously ILLEGAL ALIENS.
There are various exceptions to the English requirement, but these are insiginicant compared to these two reasons. For instance, elderly, supposedly invalid parents (who wouldn’t be buying a new house for themselves), refugees granted asylum, etc.