Yes, interesting. I think there was an active spice trading route from Japan through Xiamen hundreds of years ago. Perhaps a true international product.
The word originates from eastern China (Xiamen or previously know as Amoy), the Minnan-hua language uses kôe-chiap or kê-chiap. Originally a sauce of pickled fish with spices.
These are valid issues but no way is metro superior in every way. I have used the trams in Melbourne Australia extensively and it is generally a great experience. You feel part of street life. Just jump on and go a few stops if need be. For longer distances it sometimes turn into light-rail that is separate from the road e.g. down a median strip in the middle etc. With city centres becoming better, more pedestrian focused and less car orientated, trams are awesome. I think most subways around the world are depressing, functional things. There is room for both.