At an event where you hardly know anyone in your 20s: Your adventurous and free-spirited nature is a given. Or, no-one’s really noticed you’re there. Or, no-one really cares.
At an event where you hardly know anyone in your 30s: You have an awkward or intriguing backstory which must be gleaned by those who know each other.
Single in your 20s: You’re obviously out playing the field and having fun. Or, you’re in the closet. (Or, in my case, self-evidently no-one would fancy you because you watch the news voluntarily and listen to music more than a year old…).
Single in your 30s: You’ve obviously recently split up with your fiancé/the love of your life. There, there. Slightly more flattering than above in that it assumes you’ve had sex (and may be followed by a flattering appearance-related remark), but no less tricky if inaccurate.
Not driving yet in your 20s: Who even cares? Nobody asks, especially if you’re in London, or your university town’s the size of a matchbox.
Not driving yet in your 30s You’re obviously an alcoholic and/or you’ve been banned for running over a child, you’ve got a medical condition which makes it difficult. (The third is the most common but the least-assumed, FYI…)
In your 20s and work with young people: Yay, a vibrant office of like minds!
In your 30s and work with young people: What, you expect me to accomplish things with people who aren’t old enough to remember Brookside??!!