But then, the really good Java (or Scala, or whatever GC-based lang) programmers are the ones that actually know and actively take into consideration how the GC works memory-wise and speed-wise. The same kind of thing can be said about interpreted langs and speed. Of course, that kind of thing also happens in C++, good C++ devs know the order of any instruction speed and memory-wise, but it is much more evident in C++/Rust and it's actually documented in the standard libraries, and the lang itself tackles the problem.
Yes, with age and experience comes the ability to predict where things will need attention, but in the vast majority of cases memory management causes no issues -- which is why the language gets out of your way so you can focus on the business problem (which causes bugs and other issues millions of times more often).
Exactly. Which is the core of "not worrying about it". When it becomes a problem (Such as an out of memory exception) you worry about it. There is no illusion. The time you don't worry about it is when you write it. I'd write it exactly like you did above (except I probably wouldn't null it), and wouldn't think of it again until it became a concrete problem.
You are absolutely right that a GC didn't magically make all memory issues disappear. It just hides them.