Foreign language yes, but art? I could memorize a bunch of facts about art, styles, etc. But that's not the same as doing well in the class. I could be a brilliant artist who learned a lot in the class because the teacher motivated me but I have no idea what the difference between penciling vs stenciling. (I have no knowledge of art, I just said that example as something that sounds similar but could be very different).
Most education in art focuses on the technical and contextual (history, styles, etc) aspects. The contextual aspects lend themselves quite well to standardized testing.
The technical aspects don't lend themselves very well to a "fill in the bubbles" test, but that doesn't mean they are subjective. Testing them would be more difficult, but it is routinely done.
