The bottom portion of your garage door is most susceptable to this kind of wear which can lead to water damage and wood rot.
Garage door exterior surface cracked.
Wooden door patch repair an old wooden garage door made of fiber board wood or other composite wood materials can become warp and receive water damage from years of rain and snow splashing and pelting its surface.
Actually fixing a crack in a garage door panel can be a difficult and even impossible task.
You are more apt to see these types of cracks on a garage floor that has a hard smooth troweled surface than one that has a broom finish.
Caulk paint cracking or crawling the cracking of the paint film over a caulked area.
Loss of caulk s initial adhesion and flexibility causing painted caulk to crack and or pull away.
Gravel and or sand on top of the sub grade.
Repairing the doors requires a little work and depending on how large the crack is could be.
If the garage door panels are wood then yes a garage door panel that is cracked could be fixed using wood fillers and glue.