Why is there no language that can run on a GPU, not considering GLSL and the such as they're shader languages and are only used for that.

open cl?

"run on a GPU"...

Maybe reverse question: What is a GPU and what is a CPU?

Are you asking why you can't just take a piece of code in a well known lang like java/python/c++/c# and say "run on GPU"?

Because unless you're writing shaders and making use of the concurrency features provided by GLSL the GPU is worse in every aspect than the CPU. However, there are technologies such as CUDA that introduce these concurrency features into more general-purpose languages.

binary ¯\_(ツ)_/¯

there are languages that do but perhaps your question is more about why GPUs are not used for genersl purpose computing?