Once upon a time very long ago, in the early to mid – 1900s, kosher butchers sold meat that may or may not have been considered glatt.
Are you referring to Ashkenazi Europe where Glatt was a virtually unpracticed Chumrah (at least amongst the religious masses) or to America where there was so much corruption that the Ridbaz fled Chicago with his family on Shabbos because their lives were in danger.
Today’s standards of kashrus are higher and virtually no frum person I know of would consider eating meat that is not certifiably glatt kosher.
None of the Hashgachos I use would certify non-glatt meat but if a Shochet I trust would end up with non-glatt meat, I wouldn’t hesitate to eat it.