Retired English Teacher
The first time someone hears a new term, they may have to learn the meaning the same way they would with a new word, but it would normally be in a context. Road rage is fairly new, but once the idea caught on, we suddenly had a new family of rages. If someone used the words alone, the meaning might not be clear, but if they told us that a driver had got out of their car and attacked them and used the term, most people would know what it meant.
We need new terms all the time, and they can be disseminated very quickly through the media, internet, etc, so a new compound is rarely a problem for long even when the meaning isn't crystal clear on first hearing.