That in itself is scary because Git refs are mutable. Even with compromised credentials, no one can replace artifacts already deployed to Maven Central, because they simply don't allow it. There is nothing stopping someone from replacing a Git tag with one that points to compromised code.

The surface area is smaller because Go does locking via go.sum, but I could certainly see a tired developer regenerating it over the most strenuous of on-screen objections from the go CLI.

Let's say you need a FFT implementation. You can write that from scratch, or you can use a library. In both cases you should use tests to verify that the code calculates the FFT correctly, and in the library case you should read the code to make sure that it works correctly and does not omit and edge cases (e.g.).

If you care about security, you only have to care once, during the audit. And you can find a pretty high percentage of malware in practice without actually having a detailed understanding of the non-malicious workings of the code.

Libraries allow you to not think about what the code does at development time, which in general is much more significant than audit time. Also, importantly, they allow you not to have to design and write that part of the code.