为什么对身体好是be good for,而对身体不好是be bad to

Salty food is bad to your health.

It's good for you.

be good for后面接人
be bad to后面接的是健康之类的具体内容

bad to the bone坏到骨子里
Reading in the sun is bad for your eyes .
Eating too much for super is bad for health .
都可以用for

看看这句话
Internet content filters may be bad for one's health

用for后面加名词
to后面加动词原形吧

对身体不好~一般用 be harm for .
身体好是be good for

be good for 后接人，为范指，而be bad to后接具体部位，为具体。

是这样的，这是有两个不同的词组，
一个用be,一个用do
be good/bad for your health
do good/bad to your health