Maven does not recompile everything each time. You have to do mvn clean to force it to. If you change a single class just that one class gets recompiled which is evident by Maven's output.
"true (default) in this mode the compiler plugin determines whether [...] any source file was added, removed or changed since the last compilation. If this is the case, the compiler plugin recompiles _all_ sources.
Yeah, although my experience is that people collect shell aliases and similar workflows that always do something like `mvn clean package` and then complain about build times.
Also, while I love Maven, I don't run it very often (or at least not directly on the command line). Most work happens in IntelliJ, and then I'll let the build server deal with it. Builds are short, so no harm if the build server fails and I have to fix something up...
