People lie on their resumes.

There's a huge surplus of people claiming skills they don't have. You'd be shocked at how many people who claim to be strong data scientists don't know SQL.

When I last hired for a technical position, I had half an hour for each candidate to decide whether to move forward with them. I wrote up seven questions that took fifteen minutes to answer. I also spent fifteen minutes talking about the job, the co-workers, and answering questions about the fit of the position.