I think that other knowledgable umpires have made some pretty good comments here. I wanted to take a minute to make a few general statements that apply to all rules and to all plays. First, the rules exist to create a fair balance, literally a fair playing field. Rules exist to prevent a wrong from occurring and to penalize offenders when they do occur. They are not designed to award or penalize above and beyond fair play. Second, not every "unfortunate" occurrence on the field requires invocation of a rule, and ultimately a penalty. The field is designed such that things can occur that aren't Kosher, but don't require a penalty. Third, umpire's need to keep the phantoms in the bag. Part of being a good umpire is knowing when to get involved and when to stay out of it. No umpire should be afraid to make a controversial call when necessary, but it's worse to make a call on something that didn't exist and it is not to make a call on something that didn't. It's one thing to miss something, it's quite another to image something. Lastly, rules don't exist in a vacuum. Rather, rules build on each other. Anyone looking to understand a rule must first start with the definitions relevant to the rule. They must understand the definition and its words and not merely brush over the definition. Here, you have to know who a batter-runner is, what the three-foot lane is and where it is, what interference is, what three-foot lane interference is, etc. These all build upon each other. You can't have three-foot lane interference if you don't have "regular" interference.
These are just some thoughts that might be helpful to keep in mind when approaching these situations.
These are just some thoughts that might be helpful to keep in mind when approaching these situations.