ni taishite VS ni totte

This is a grammar thing that i can't get my head around and I wondered if someone could explain it simply.

i understand ni taishite being as in (when dealing with) so for example 君の意見に対して。。。
客に対して。。。

now ive heard that ni totte also means something similar but is an easy grammar mistake for learners to make when it comes to choosing the right one.

Ive heard it used before in the context of 'when it comes to' so like 日本人にとって, they cant eat dairy etc.

So why cant i just use a simple は there instead? 日本人は...cant eat dairy.

In summary -

1. difference between にとって and に対して

I don't think they are very similar, though.

...ni taishite: ... in response to; in dealing with; in contrast to

- 君の意見に対して、私はこう考える。(In response to your view, this is my thoughts.)
- お客に対して、失礼なことを言ってはいけない。(You must not say anything rude when dealing with/to customers.)
- 彼は山に登りたいのに対して、彼女は海に行きたいらしい。(He wants to go climb a mountain, but (in contrast) she wants to go to the sea.)

...ni totte: ...for someone in this position; from (personal) perspective

- 日本人にとって、お盆は大切なものだ。(For Japanese, o-bon season is important.)
- 母親にとって、子供は何才になっても子供だ。(For mothers, their kids are kids no matter how old.)
- 私にとって、その古いぬいぐるみは宝物です。(For me, that old plush doll is precious.)

Now in that "can't eat dairy (products)" example, I would phrase it like:
日本人は、乳製品が苦手だ。(Japanese are not good with dairy products.)
日本人は、乳製品が消化できない人が多い。(Many Japanese cannot digest dairy products.)

日本人にとって、乳製品は余りなじみがないものだ。(For Japanese, dairy products are something that they are not very familiar with.)

My understanding is like this.
に対して　original meaning is "facing to", this phrase is used to close up the object.
にとって　original meaning is "for the benefit of --" .

They have somehow different nuance.