The use or unuse of a comma before "because"

[Deepurple]

Hi, I've come across an explanation about the use or unuse of a comma before "because" that would make a difference to the meaning of a sentence.
To illustrate, may I quote the example of the book at here:

"The scheme was not approved, becuase of the shortage of water."

The author said if the comma was omitted before "because", the sentence would mean "The scheme was appoved for some other reasons than the shortage of water." His reasoning has not got across to me until now, and the use/unuse of a comma before "because" has confused me for ages.
Would anyone have a go at that? More examples of the use/unuse of a comma before "because" with explanations are appreciated. Thank you.

[Tdol]

The author has a point, though I am not sure that every person would punctuate in this way to avoid creating that meaning. Also, the context would have to have something before or after it to make it clear that there was another reason IMO

[Deepurple]

Originally Posted by Tdol

The author has a point, though I am not sure that every person would punctuate in this way to avoid creating that meaning. Also, the context would have to have something before or after it to make it clear that there was another reason IMO

Could I infer the use/unuse of the comma before "because" in this way?
Hm... Is there anything to do with the so-called "negative transfer"?
For example, I don't think he is a good father => I think he is not a good father.

Ambiguities may occur if a comma is omitted in such kinds of negative sentences as in "The scheme was not approved because of the shortage of water." => "The scheme was approved not because of the shortage of water(but for some other reasons)."

In order to avoid the ambiguities, we have to punctuate the sentence before "because" => The scheme was not approved, because of the shortage of water. The "because-clause" has now become an supplementary information, an only answer to the disapproval). Was I getting it right? Thank you.