Both the Japanese and Germans expected very short wars, and entered the conflict with superior weapons with which they expected to win.  They concentrated on producing more and more of them, didn’t engage in much R & D until too late.

The Allies started the war with older designs and inferior weapons.  Therefore they had to develop new designs and then focused upon improving them.  Especially the Germans, had they spent resources early in the war, would have developed weapons which might easily have forced a stalemate.  The German rockets, airplanes, tanks and submarines were better at the end and they had radar earlier and in shorter wavelengths than the British.  They were just very poorly organized to utilize it to the fullest, a notable success of the Brits.