As a generalization it’s true. As we all know, not all generalizations are always true though. Look at people in the same career line, or groups of friends, there usually are outward cues that lets us know they belong to that group. Clothing styles can be preppy, motorcycle, edgy, ratty jeans and t-shirts, designer jeans and t-shirts, polished, revealing, modest, etc.
People with similar interest tend to get together also in groups. Church groups, social groups, people who like to fish, race, travel, have young children, like the arts, and so on.
When you look at someone do you kind of size up whether they are likely similar to you? It’s not a good way to go in my opinion. If yiu never talk to the people who don’t look like you you can miss out on a lot of gat people, and you can miss people who actually are very similar. But, I think people do it, especially young people.