My gut feeling, pun intended, is that if we were meant to get thousands of units of D orally, food or otherwise, you would find it in nature in our food supply. Other than extreme and rare foods like fish liver, etc., most foods have modest amounts of this hormone compared to other fat soluble vitamins. I just don't believe we need to get the amounts they say we do, and it is evident that nature offers it in the highest amounts via sunlight/skin production. I think that low D status is not the cause of disease, but the result of it, and few are taking into account of the active form of D which can be high when storage forms are low.
I think sunlight does not have the calcium promoting phosphate reducing effect oral vitamin d3 has?