That's moving the bar though. Only in the past decade or so has it become reasonable ("reasonable") to include entire runtimes together with an application. Java started in 1995, Python started in 1991. This was an era when one of Java's main targets was SIM cards and other highly minimal devices, so not only would the target already have a JVM, but it would be wholly impractical to ship your own. Even on desktops, downloading just a fraction of Java for each program would be a massive waste of limited bandwidth and disk space.
For that reason, Java and Python didn't start out with fully self-contained bundles as a design goal. It just wasn't practical in the 90s. Obviously, yes, if they had managed to correctly predict and plan for three decades of technological improvement, then sure, we'd be working in a very different technological landscape. But they couldn't possibly have, and solutions built on the old languages are always fraught with disagreement. So, we use new languages, like Go and Rust, which are developed with modern needs in mind.
For that reason, Java and Python didn't start out with fully self-contained bundles as a design goal. It just wasn't practical in the 90s. Obviously, yes, if they had managed to correctly predict and plan for three decades of technological improvement, then sure, we'd be working in a very different technological landscape. But they couldn't possibly have, and solutions built on the old languages are always fraught with disagreement. So, we use new languages, like Go and Rust, which are developed with modern needs in mind.