What airlines allow the F/O to taxi the aircraft from the gate to the runway? Is it in the airline's operations manual? Is this a good idea?
It takes around 4 sectors to teach a F/O even with low hours to taxi a narrow body like the A320. Another few sectors then to start managing the brakes in a proper way but this is another big topic. So it's not a big deal at all, especially because the Captain is always there to share his experience with a new "taxing" F/O, just like in any other phases of flight. It might get tricky sometimes with narrow runways, at night, in poor weather conditions etc.. but these are exceptions. Personally I don't see any problems with the F/O taxing.
Cheers.