Yup, the government did do something. But don't know that "wide variety" is a good description for requiring that it be added only to certain grain products.
The result is that even a pure junk food diet will result in sufficient folic acid intake.
Sufficient for what? When I googled this just now I found that the new program was designed to add only 100 mcg folic acid to existing intakes.
The CDC believed that 400mcg of folic acid daily would be enough to prevent neural tube defects in most women. But the new program only has the rate down by 25%. That means either the CDC estimate was way off or the enrichment program isn't getting women close to 400 mcg. My guess would be that the latter is more likely explanation.
The neural tube stuff doesn't apply to me. I take a one-a-day vitamin anyway and think everyone should.
http://www.fda.gov/oc/history/makinghistory/folicacid.html
Per the above history of the folic acid issue, there is some concern about possible dangers of excess folic acid intake, so perhaps that's why the fortification has been on the low side. When it's in a large range of snack foods, a signficant number of people could get too much, even while many were getting less than the optimal amount. It's obviously a complicated issue.
I started taking 400 mcg of folic acid daily when I was 14, based on Adele Davis' books, which suggested that the fear of masking B12 deficiency was overblown (and it certainly is when you're talking about people who are using supplements of various kinds). Seems to me that problem could be completely eliminated by adding B12 side by side with folic acid, but appraently there are also some other potential problems associated with excess folic acid intake. Presumably the details of the fortification program will continue to be tinkered with.
P.S. Towards the end of that history, it appears to say that the final level chosen was for breakfast cereals to contain 100 mcg per serving (and as we all know, official serving sizes are usually smaller than what people actually eat), and that other grain products are also fortified, apparently at similar levels. So I don't think the program is designed to provide only 100 mcg per day.
I guess it will take further research to figure out why current supplementation levels have only reduced neural tube defects by 25%. Could be that the segment of the population which is most prone to neural defects also has some atypical eating habits, for cultural/ethnic/geographical reasons, and/or is prone to other lifestyle factors that contribute to neural tube defects and/or interfere with absorption of folic acid (e.g. drug/alcohol use, obesity, etc.).