I think this is because of the gap in its target market -- Rust is firmly positioned to replace C and C++, which have a long history of safety issues. Kotlin is positioned to replace java, and besides a few quality-of-life improvements, it changes some syntax but very few semantics, so the gap is much smaller. Go was originally pitched as a C or C++ replacement, and it's very nice for deeply parallel programs like web services, but its big runtime and its GC rule it out for a lot of (especially very low level or latency-critical) uses -- you don't see Go ported to microcontrollers for instance. I can't speak for Scala, because i don't have experience writing software in it.
To summarize, Rust provides a lot of compile-time discipline that C and C++ are lacking, and many people are tired of maintaining code that was developed without that discipline. Rust makes it harder to write low-effort software.
As a programmer that picks up a new language every 2-3 years (and one that is privileged to have an employer that tolerates this) Rust is really a breath of fresh air; not because it's easier, but because it codifies and enforces some good habits in ways that other languages don't.
To summarize, Rust provides a lot of compile-time discipline that C and C++ are lacking, and many people are tired of maintaining code that was developed without that discipline. Rust makes it harder to write low-effort software.
As a programmer that picks up a new language every 2-3 years (and one that is privileged to have an employer that tolerates this) Rust is really a breath of fresh air; not because it's easier, but because it codifies and enforces some good habits in ways that other languages don't.