Why isn't there only one programming language for any kind of applications or computer programs?

Question

There's many programming languages to learn! Swift for iOS, Android studio for androids, C++ for computers, Java script for sth else and etc.
Imagine you only had known C++ and you could have write any type of program for example for android, for iOS and for computers ....
Wouldn't it have been easier if it had been so?

Answer 1

because everything is written on its time.
some programming languages are older than the platforms you mentioned, so they were not designed with that in mind.
creating a new one seems ideal than making the old ones adequate.
the difference is just in syntax and compilers and runtime mechanisms.
in the end they are all converted into machine code.
not to mention that some programming languages are proprietary you can't just use them because you like them.
the war between oracle and Google for example, over Java. pushed Google to make Kotlin. same pushed Microsoft to make C#........