[novok]

RDIs are based on an 'average american' diet. What you actually need nutritionally can change significantly based on your diet specifics.

For example if you have a diet high in oxalates, which are present in many leafy green vegetables, then your nutritional requirements for things like calcium and magnesium are increased, because the oxalates bind to the calcium and magnesium and cause you to not absorb it. Thus to compensate for that effect, you need to eat more of that nutrient. If you have a diet free of oxalates, then the amount you need is less than the RDI, etc.

Also a lot of nutrition labels do not modify themselves on the bioavailability of their specific nutrients. Plant protein is less bioavailable and has a less balanced amino acid profile than meat protein, so you need to eat more plant protein typically to get the same total equivalent amount to be absorbed by your body. Magnesium oxide is cheaper than magnesium citrate and is not absorbed enough, so you need more magnesium oxide in weight to have the amount absorbed by your body be the same as a lesser amount of magnesium citrate. But on nutrition labels, they're just going to put milligrams of magnesium, no matter what kind there is.