Yes, acceleration is a thing, but trains a)reach a top speed and spend a lot of fuel maintaining it, and b)reaches much, much lower top speeds, with any effort to increase it requiring exponentially more fuel to reach and maintain. Air resistance is an absurdly important factor to travel efficiency.
The ISS travels at a constant speed in relation to the earth. People have to get on and off a train
Yes, acceleration is a thing, but trains a)reach a top speed and spend a lot of fuel maintaining it, and b)reaches much, much lower top speeds, with any effort to increase it requiring exponentially more fuel to reach and maintain. Air resistance is an absurdly important factor to travel efficiency.