I think the issue with string_view is less laziness and more recency: most libraries still need to support C++ versions prior to C++17. Rust had the advantage that slices were there from day one.
While using C++, adding something like gsl to the toolbox is worth gold, and also enabling bounds checking even in release (really, most of the time it hardly matters to the application users).
"C++11/14 at Scale: What Have We Learned?"