Getting hit on as a woman?

What decides whether or not a man hits on a woman? Except smiling. I’m at a bar rn in a big city and trying to look “approachable” but no one is coming up to me. Have men just decided to rely on dating apps or what? It’s kind of sad how I used to take being in a serious relationship for granted when I was younger. It’s really, really, really, really hard and challenging to have a boyfriend the older you get. I just turned 29.