In CA maybe, up here in the rainy NW it traps water and they rot off quicker.
Gravel or sand.
There are many techniques for overcoming concrete/wood limitations in wet environments. There are techniques with the concrete post process that lets it be used on about any type of terrain. Some modern solution's put a gravel/sand combination in the bottom of the hole, set a PVC sleeve in the concrete and let you put a fully sealed pressure treated post into the sleeve. It's easy to replace, pretty much dumps all the moisture down into the gravel/sand. The exposed portion of the post needs to be kept fully sealed or treated regularly to keep the wood from absorbing excess moisture as well.
Is it always the best solution? No, it can be very expensive and labor intensive to do at times.
Driving doesn't always work in rocky soils, but it's actually a solution I like. I'm not a fan of the cable hammer drivers but the pneumatic ones are pretty quick.
If your tractor is heavy enough, you can make a hydraulic ram post driver. My Grandfather did just that and used what is now my, AC D-17 backhoe (9000 lbs) to drive several miles of T-post fencing with it. I wish I still had that driver but my grandpa disassembled it to use as parts on other projects. My father was going to recreate it but never got around to it. He has a T-post that it drove AROUND a rock about 1' in diameter. When they pulled the post out, it pulled the rock up with it. The post actually conformed to the rock. I'm heading back to my father ranch for Christmas, if I can find that T-Post I'll get a shot of it. It may not have survived my fathers scrap purge of 2014 though!