Everybody produces bugs, but Claude is good a producing code that looks like it solves the problem but doesn't. Developers worth working with, grow out of this in a new project. Claude doesn't.

An example I have of this is when I asked Claude to copy a some functionality from a front-end application to a back-end application. It got all of the function signatures right but then hallucinated the contents of the functions. Part of this functionality included a look up map for some values. The new version had entirely hallucinated keys and values, but the values sounded correct if you didn't compare with the original. A human would have literally copied the original lookup map.

When you write the code yourself you are slowly building up a mental model of how said thing should work. If you end up introducing a subtle bug during that process, at least you already have a good understanding of the code, so it shouldn't be much of an issue to work backwards to find out what assumptions turned out to be incorrect.

But now with Claude, the mental model of how your code works is not in your head, but resides behind a chain of reasoning from Claude Code that you are not privy too. When something breaks, you either have to spend much longer trying to piece together what your agent has made, or to continue throwing Claude at and hope it doesn't spiral into more subtle bugs.

simple: people produce subtle subtle bugs, LLMs produce obvious subtle bugs.