Java's a pretty extreme outlier for late or non-adoption of modern features, but it is true that Java is the closest direct competitor/peer to C# in terms of usage/marketshare. C# seems to be steadily shifting from being a language which initially (v1.0) looked like Java to one which looks increasingly like Scala (e.g. addition of pattern matching, tuples, local methods etc.).

Java is generally C#'s main competitor. Comparing them is the most appropriate comparison.

Scala seems to be vastly more expressive while simultaneously having only 20% of C#'s feature set.

F# would probably be a better comparison peer to Scala than C# would IMHO