Because automatics can feel slow and laggy depending on the terrain, because they can only respond to load rather than anticipate it. In the UK and EU there are lots of hills and narrow winding roads where you notice this the most; whereas if you are mostly driving on the flat automatic probably feels no different. It's also more noticeable in small cars with small engines (also more common over here out of practicality) where using the right gear at just the right time is more important if you don't want to end up stuck crawling up a hill.
Most EVs are single speed transmission due to the wide range torque curve, so manual vs auto is kind of a moot point for all but very high performance vehicles anyway... Which is why this honda thing is a total gimmick, i'd happily give up manual gearbox when there is no performance and efficiency difference.