I doubt newspapers ever were proof-read. There wouldn't have been time. Formerly, the typesetters were experts in grammar to such an extent that journalists asked their advice if they were in doubt.
Nowadays there are no typesetters, journalists do the layout on computers and we all know what spelling checkers are like, don't we?
Formerly reputable publishing houses had proof-readers who worked in pairs. The one read aloud and the other followed the text on paper. Now there is usually only one proof-reader who both reads and makes the corrections, so more mistakes get through.