Both 737's and A320's have an airborne idle, which is higher than ground idle. However, you don't make your final approach with idle thrust. High idle on the 737 is about 30% N1, and a typical approach power setting is 55-62%. Ground idle is about 20%. Comparable for A320. In fact, if you haven't stabilised at your approach power setting by 1000', company rules say that you go around.
Thus, response to go around power is only about three seconds - less than the length of time it takes to pitch to go around attitude.