Aside from what others have said, the single tiny binary and cross-environment compilation is a huge plus. I can compile my largest service in seconds for Windows, Linux, and Mac (we still use Docker, but not for the cross-environment reasons). It's simple, concise, and fast out of the box. I also have been bitten far too many times by the JVM being RAM hungry and, frankly, I focus on startups which don't have time or resources to spend tweaking VM variables. Granted, I am sure Java and the JVM have come a long way since I last used it heavily in 2013, but I haven't found a single reason to want to go back.

As far as Python, same kind of reasons. Single binary makes deployments easy, static analysis and built in tooling makes life easier, and I just find it more enjoyable, which is completely subjective.