Re: Why do some plants need more light than others?

The question might be better posed as: Why do some plants need less light
than others?

Plants have adapted to a wide range of light intensity, quality, and 
quantity.
Some plants grow in areas that NEVER receive direct sunlight; others
adapted to growing in deserts where they almost always receive intense
sunlight; others grow near the poles where they might not receive direct
sunlight more than 3 months/ year; others grow in understory [beneath other
plants so the light they get is 'passed through' by other plants].

All plants need sunlight to carry on photosynthesis. Some plants are
parasites that lack chlorophyll but depend on other plants that carry on
photosynthesis for their 'food'.
Adaptations in the plant's chloroplasts [light gathering organs for
photosynthesis] make it possible for some plants to reduce carbon dioxide
to make sugars and acids under lower light conditions than other plants and
for some desert plants to do this at night when temperatures are lower and
the risk of water loss is less.