For C++, the classes and objects are built from traditional non-OO approach, whcih means those classes are "translated" into pointers, structures, method tables and then compiled into binary code. Translation is only triggered when the compiler see the "class" keyword.

For Java and C#, such translation is implicited by the root Object class, which will define the basic methods, memory structures and pointers. In another wod, the compile always does such translation.

So it is not the case that Java and C# won't work without a library. Instead, they choose to treat everything as object and imply such translation in the compiling process.

P.S., don't say your point is only for the current languages... that makes your initial point sucks.