You have to have vitamin D or you can eat calcium all done long and it doesn't do any good. That's why milk is fortified with it.

Very true, and important.

Soy products like tofu are actually a more concentrated source of calcium than milk products are.

Not naturally, they're not. Soy products originate with much lower Calcium levels than does milk. The Calcium in soy milk, tofu, etc., nearly all comes from supplementation. Soy as a source of Calcium can just be thought of as an inefficient, diluted supplement with drawbacks. It is easier just to buy supplement pills, and avoid all the associated negatives soy products have (undesirable estrogen analogs, nutrient blockers, digestive disturbances, quick-rancidity oils, etc.).

You might want to read the post I made above earlier in this thread on how undesirable soy products are for human consumption.