Who owns these undeveloped lands though? Are they private but just not focused on by the owners?

Could there be loss of ownership (i.e. deceased) or are the lands embroiled in court battle?

I assume the bandits are a consequence since they use the vast forestry as hideouts. Or do they threat even the landowners which is also one of the reasons it's being left untouched. Maybe waiting for a buyer to take the risk of developing it?