Thanks everyone for your thoughtful responses. It's great to hear from people actually working in the industry, as a journalist I speak a lot with sales engineers for the big vendors/OEMs, and they don't have the same insight....
Which do you think is the higher level proprietary one? The super polished drag and drop type interface? Or languages Like Karel and Rapid?
To clarify, I meant "higher level" in the sense of "further removed from binary". For example a language like Python is abstracted from machine code to provide features and be easier for people to read/write, while Assembly for example allows for operations that are "closer" to the actual hardware instructions.
Skyefire pointed out above that robot languages have evolved separately from computer software languages, so I don't know if this is the correct usage. But in short I would think that the more "user friendly" an interface is, the more translation the computer/PLC is doing to get it down to the binary instructions that the controller actually follows.