One of the really interesting things about BASIC is that there are probably more dialects than any other programming language. Perhaps this is because BASIC really is the people's language. Sure, there are different versions of C (a few), Cobol (why?), Forth, etc. but people just love to create their own version of BASIC for whatever reason.
I guess that since BASIC was born into a world where it was shoehorned into many, many different computers it became part of the BASIC culture that it is okay to have many broadly different implementations. Every early home computer had it's own BASIC.
Now I've heard it said that this is a weakness of BASIC, and many people complain that there is no commercially viable standard BASIC. I'm not sure why this is a problem. The standard (by committee) is very old and limited. Since the world is constantly changing, I think it's a good thing that BASIC hasn't settled down into a rut. BASIC is still a place where people feel free to explore and innovate.
The world is big enough to accomodate variety.