Four Speeds = Flexibility and Control
Not all trades need endless power and lots of batteries in a drill kit. Many don’t need the raw power of 18v or 24v, or the weight and bulk that goes with it! Also, Ah is not that important either - a small 4Ah cordless combi can last for several days on a job.
With a smaller driver what you should get is precision control. Two speeds may be enough on an 18v drill, but control and accuracy are required on smaller fitting - enter the 12v machine.