Like the title says... C++14 is C++; soon this will be C++17.
Java submissions aren't restricted to java 3 or 4 or 5 or 6; they are compiled and run on Java 8 - as of now the latest version of the Java standard. Why then can some problems be restricted to being solved in an archaic version of C++ instead of making C++14 the default C++ version or at least automatically including C++14 in the list of allowed languages for all problems that accept C++ solutions?
I really doubt the authors had anything against C++14; it just didn't exist when the problems were posted.