Horse and carriage.

I watched the Oprah Winfrey show today (yes, I did, so shoot me. ;)), and I noticed an interesting (and perhaps well-known) phenomenon, namely how an expression such as "horse and carriage" not only semantically, but also formally, is treated as one single element. Oprah was talking about a 109 year old woman and said that she lived "in a time when there were still horse and carriages." My point is that she only pluralized the word "carriage". Had she pluralized "horse" as well, and said that "she lived in a time when there were still horses and carriages", she would have seemed to presuppose that we don't have horses anymore. In other words, she would no longer be referring to the expression "horse and carriage", but to horses on the one hand, and carriages on the other. I guess that this is one example that supports the view of certain linguists that go as far as maintaining that it rarely makes sense to scrutinize language on a word-level, that in expressions such as this one, each individual word has no meaning of its own, only the expression as a whole. I disagree with this view. I still think that the individual words that make up an expression contribute to its overall sense. Any opinions? And, can you think of more examples such as this one?