Why do people say "let's hang out soon" when they don't mean it?

I’ve noticed this a lot lately, especially after meeting new people or catching up with old friends. Someone will say, “We should hang out soon!” but then nothing ever comes of it. It feels like a polite way to end a conversation without any real intention behind it. Have you ever experienced this? I’m curious why this happens and if there’s a better way to handle those situations without feeling like you’re being brushed off.