There is a HUGE difference between the RDA of most vitamins and minerals and the Optimum Daily Amount (ODA) that gives maximum health benefits. As it is, the diets of over 90% of us are deficient in in just the RDA. The RDA is almost impossible to obtain via diet on a daily basis and the ODA is out of sight.
Sunlight is indeed by far the best source of Vitamin D3, but very few people get enough sunlight. People above the 35th parallel get virtually no Vitamin D3 from sunlight during the winter months and it is very difficult to get the optimum amount from your diet.
The reason we don't protest the quality of our food more is because few are aware of the problem. Sadly, many of the ones that are aware an/or concerned seek to get their missing nutrients from synthetis petro vitamins and crushed rocks minerals (the majority of which come from the land of lead and Melamine).
The best way to get most of your vitamins and minerals is to grow your own produce (can and dry as much as you can for the off season) organically in soil that you have amended with minerals. Soil in the home garden should only be tilled once in the original preparation and top dressed thereafter for maximum soil microorganism activity and nutrition. If you have access to leaf mold in a forest and dried cow manure from free range cattle which graze on land unadulterated by pesticides and herbicides you have a bounty for your garden. Back before the feedlot practices became so horrible I liked to go to the local chicken produce house and get chicken entrails to bury deep within the soil underneath tomato plants. I am sure the same could be done now if you raise your own chicken, or go fishing and clean a bunch of fish.