"you"+negative for general statements

Question

• I know you don't often see a red cat on a bicycle.
• He understood that you shouldn't talk loudly in the library.
• She learned that you mustn't throw charged batteries into fire.

Does the "you" + negative do,must,should,etc. mean that it's a general statement that concerns everyone?

I mean that this - "The teacher told us that you shouldn't drink coffee in the evening" means that 'in general no one should drink coffee in the evening'.

Here "you" simply means 'everyone'?

Answer 1

Your examples all seem right. The word "you" can refer to the person being spoken to, or it can refer to a person in general. This is true for both negative and positive statements.

She learned that you need flour to make cake.

is just as correct as

She learned that you don't need red dye to make a good cake.

Using "you" as a general term for anyone is an informal practice, which is very common in spoken English but somewhat less common in written English. The formal (but rather awkward) alternative is "one"

She learned that one must always mind one's step at the amusement park.

This is quite uncommon in spoken English, but proper in formal writing, even if it is rather cumbersome.