In contrast, GTK is written in C AFAIK, and anytime a new language springs up the very first thing you generally see is a GTK wrapper. I have always suspected this is because C is far easier to wrap since most languages have a well defined C FFI, but typically lack a C++ one (due to lack of std ABI) thus Qt/wxWidgets bindings typically lag GTK.
Qt on the other hand is very much a C++ OOP style, so if there's an impedance mismatch representing that in your language, as is the case for Rust, C or Go, then it gets much harder to do. The C++ bindings do present difficulty of course, but you can see from e.g. PyQT that if the pattern works in your language it's one that can be overcome.
So yes, there are tools, my point is it is still much easier to wrap a C based API because you can often just use your language FFI, not an external toolset.
Accessibility and internationalization are really hard though, right?
I'm finally doing something about the accessibility issue: https://github.com/AccessKit/accesskit Still have a long way to go though.
And people tend to use what they see other people using, thus repeating the cycle.
So you see these 15 year old libraries being used because other people are using these 15 year old libraries because they are written in languages that can be (relatively) easily be wrapped (both C and C++ wrapping can be done automatically and there are many tools for that - largely because this is something a ton of people want to do, so again, it feeds back to the cycle of things being popular because they are popular).
But there are lots of new toolkits being made, you can even find a submission for a new one in Hacker News almost every month (though the responses are pretty much the same in all of them :-P).