I'm wondering why the function
This has noting to do with ES 2.0 compared to other OpenGL versions.
The reference documentation shows the C/C++ OpenGL bindings.
What you're using when you call
GLES20.glDeleteTextures() are the Java bindings defined for Android. They obviously need to look different because they are for a different programming language. The Java bindings are also not standardized, so they are defined in a way that makes sense to the people responsible for Android.