the definite article in front of a noun that is followed by a defining clause

When we want to refer to a specific noun, we use the definite article 'the'. When the noun is followed by a defining clause, again we use the defining article 'the'. My question is why the following sentence does not have the article 'the'? The who-clause seems to require the article.

People who haven't got cars can't stop at these out-of-town stores

Moreover, if I want to refer to, say, some cookies that can be find at a particular store, should I say:

Rolo Cookies are cookies (that are) sold at Tesco.

or

Rolo Cookies are the cookies (that are) sold at Tesco?

Another example:

"Make that change" is a/the??? slogan written on the Oriflame eye shadow pallet.

Could someone explain why sentence #2 in the question is ungrammatical because there i is no explanation why the article is used: Use of article in front of product names