Thats because back then you got a paid lunch and in the 1990s companies stopped offering that and said it was a boon to workers because "you can leave the property for lunch" and other excuses like "liability" and such.
Now workers have to stay an extra hour and dont get paid for that time.
Even if you can leave
Unless you live really close to your work there's no practical place to even go to without wasting a bunch of your break traveling
In Australia at least, it's common for office jobs to either be 9 to 5 with a half hour lunch break, or 9 to 5:30 with an hour lunch break. Companies I worked at when I lived there (before I moved to the USA) usually did the latter. An hour break was nice because I worked in the center of Melbourne and could walk around the city, get lunch, go to the bank if I needed to, buy stuff from one of the computer stores nearby, etc and still make it back to work on time.