It's really easy to catch these scammers. Ask for a non-trivial code or work sample, something they have written. Actually take the time to read through the code and understand at least a part of it. In an interview, ask them some questions about it. People who actually wrote the code or did the thing can talk at length about about what they did, the history behind it, trade offs, have colorful stories about it, etc. I don't even care exactly about the technical details of it, I'm looking for signals that they are a liar.

If they say they don't remember, that's a red flag. If they can't describe how something works, that's a bigger red flag. You're not looking for photographic memory, but it's very obvious once you do it a few times who is real and who is lying.

It's common sense, if you don't put in at least a tiny bit of effort in your hiring process, you can only expect to attract similar low effort candidates.