Why are there so many programming languages?

Programming languages are tools, and we choose different tools for different jobs. We can use different laguages on different programming developing tools like java, C++,Go or Javascript,C# and use different ones for different projects according to our eligibility. Thats why there are different languages i programming.

not all systems can handle a unified programming language due to each systems having specific programming requirements that not all programming languages can offer, for example, when programming a Raspberry Pi (whatever model it is) for DIY projects, you can use either python or C# as far as I can recall but not java but when programming a microcontroller such as Arduino, you can a programming language similair to C++.

I hope this answers your question

Technologies vary and structures vary. Although it looks there is too many programing languages yet they are not that much

For example, most of microsoft programming languages are based on VB and C#.. MVC, Share Point, ASP.NET and all microsoft application development technologies all revolve around 2 languages and after that its technology structure

Also scripting and APIs are not programming languages, JQuery and Angular are a structured JS technologies ,, same like AJAX Gold and other APIs launched couple of years ago

Yet there is still the war between .NET framework lovers and JVM addicts, Rubby, PHP and script like languages along with many others yet similarities are the most and business needs along with technology needs are the driver for all those languages to evolve

Well, a good explanation of this issue can be found here. 

Every programming language has got it's purpose. We have general purpose programming languages such as C, C++ etc... However these languages may not give the stipulated resulton high end applications or even if it gives, the coding is going to be tedious. Hence to make coding easier and user friendly, many other programming languages came up.

Quoting few examples, I hope the readers will understand clearly.

.NET is the framework for web designing. C# dotnet, ADO dotnet, Asp dotnet are the programming languages associated with .NET framework to develope the webpage of our choice. 

We do have HTML for web page developement. However , .NET has many add ons or built in functionalitites that can ease our job. 

SQL server is a database designing and programming tool where MY SQL is the query language.

Java used for web design and programming is a very powerful language used worldwide.

opencv is a dedicated software used for image processing research and developement. Matlab is also on the same grounds having millions of  built in functionalitites

Every  programming language has got it's purpose.

because that is business, all languages translated into zero and one.