And the tricky part is if, say, you know that "bulldozer, backhoe, crane" are working vehicles, so it is one potential grouping, and you also happen to know that "parakeet, magpie, crane" are birds but you don't know what "finch" is and looking it up feels like cheating, so you just guess. So you guess "finch" is a vehicle and bam, wrong.

Sometimes you can use process of elimination with the other groups, but if you can't solidly make a group of four (especially if you know you, say, have a potential bird group but you are aware you do not know that many birds; and likewise with a potential working vehicle group) you often end up guessing.

And sometimes I just cannot figure out what category they are going for, even if I could place it given the category name. I am a native English speaker and like to think I am not below average intelligence.

Ya that all makes sense. And I can see it when viewing the answers too. I just need to be allowed more wrong attempts to solve.

The one that got me like that was a couple of days ago. It was jug band instruments, and jug was one of the options but it went with something else, and it took me a while to figure out it was saw.

I sure do. And I can understand the groups afterwards. I think it’s just a struggle for my personal style of thought and analysis. I look at the words and can really only think of how to group them by related definitions. I still enjoy trying the puzzle though!