Why is burning down houses illegal?
It is arson. Arson is a crime and results in prison time. When a arson fire is set it can destroy an area or town.
How do people destroy the taiga biome with man kind to make houses or stuff like that to destroy the taiga biome houses to all kinds of animals to get there way and hurt the animals by killing things?
Burning money is only illegal in some countries. However, in those it is illegal in, it falls under the category of "defacing or damaging" or otherwise making the money unusable. This is not only applied to burning; damage to some parts of a banknote can be used to cover up counterfeiting and other fakery.