In all fairness, in the 20th century (at least the first part), most Jews in the world relied on “ingredient kashrus”. They look at the label for known non-kosher ingredients. At first there were very few products with formal hecksherim, and even fewer where the item being sold has a kosher label. Even today, many people rely on ingredient kashrus rather than demanding a hecksher.
But now we can find almost anything with a formal hecksher, including most types of alcoholic beverages. And since food processing is much more complicated, labels are more unreliable than ever. So not insist on a hecksher?
Ingredient kashrus belongs to an area where Jews had to shave and try to look like goyim to keep jobs, even if it meant walking three hours to get home on Shabbos during the winter when work ended too late to use transit (and considered yourself fortunate to have a found a job that didn’t require working on Shabbos, since a six-day, 54 hour work week was the norm). It is from an era where wearing a yarmulke in public put you at risk of bodily harm, and precluded almost all possibilities of employment other than working for a frum owned business or a frum institution.