This is most probably more linked to Java/Kotlin vs Objective-C/Swift. Want an array of 1000 objects in Java ? You'll endup with 1001 allocations and 1000 pointers.
The advantage of Swift/ARC is not that it uses less memory per se but that it has a lower high water mark because memory is freed much sooner.
Java makes a lot of memory guarantees that are hard to make efficient. Specifically in that it becomes extremely hard to have a scoped allocation. Escape analysis helps, but the nature of Java's GC'd + no value types means it's basically never good at memory efficiency. Memory performance can be theoretically good, but efficiency not really. That's just part of the tradeoff it's making. And nearly everything is behind a reference, making everything far larger than it could be.
Compaction helps reduce fragmentation, but it comes at the cost of necessarily doubling the size of everything being compacted. Only temporarily, but those high-water spikes are what kicks things to swap, too.
Object-oriented programs in Objective-C are written in a very different fashion from Java programs. Java programs tend to have very fine granularity on their objects. Objective-C programs tend to have interfaces which are bulkier, and larger objects.
That is partly why you can have a high performance 3D API like Metal written in a language such as Objective-C which has very slow method dispatch. It works because the granularity of the objects have been designed with that in mind.