There really isn't a problem because the unplayable lie rule handles any unrecognized special situations on a course. However, if there are regular situations on courses like some you mentioned, the course pro or TD has the option, in fact responsibility, to specify relief rules in advance such as going to a drop zone, playing from behind a well pit (which is a safety issue that should be handled anyway) or playing UP on a higher playing surface such as a wooden deck where a disc can slide under. For example, we have a small elevated footbridge on my local course where the rule is players may play up on the bridge without penalty if they are directly under it.
It's unlikely you will see phrases like " free relief to a safe lie" written in the rules for the same reason only the player can determine what's a playable versus unplayable lie. These are slippery concepts for a group to decide for another player.