Between home and 1B there is no safe place for BR to retreat to. She can't go back and stand on home plate to avoid being put out. :D

Nor can she retreat to safe haven at 1B (if forced), but there's no rule preventing her from stepping back from a tag between 1st & 2nd, even if forced.

While I generally agree this isn't a good rule, and it sure as hell isn't interference (in my opinion) to simply delay an apparent out for a strategic advantage, there is a key difference between these cases. It isn't EVER possible for a BR to be safe back at home; but it IS possible a foolish defense can misplay a retreat to 1st by removing the force.

Hmmm... I thought I said that... ;)

A valid base-running move is for a runner between 1B and 2B to attempt to get caught between bases to attract the defense and allow a runner from 3B to score. She has no intent to advance or retreat to any base. It is basically a sacrifice. Why is the same maneuver illegal between home and 1B?

Which is why, in baseball, a BR who retreats (legally, I might add) back toward home to avoid the tag is ruled out when he reaches the plate.

I also agree with others that I find no logical basis for ruling Interference on this play. For whatever reason, softball sanctioning bodies feel this situation is a special case that doesn't apply between any other bases. Fine. But rather than ruling it Interference, why not just rule it similar to a three-foot violation, call the BR out, and leave the ball Live to make plays on other runners? If this is really Interference, then all similar acts (e.g., the aforementioned three-foot violation) should be treated as Interference as well.

As we all know, the ASA rulebook spawned all the others. While I'm old enough to have been there, I know it was before I was involved in the rules process; Mike, can you research your collection to see when this rule was added as interference? It would have to be before the NCAA rulebook separated, and probably before there was an NFHS rulebook.

As is prevalent (more so in NCAA today, with a small committee, and highly influential coaches; not so easy in the ASA 300+ voting member council) in the rules process, there can often be a bad rule or interpretation that is championed by someone with enough juice to make it a rule. Often these are changed back later, when the body realizes it is a bad rule; sometimes, it just stays with lack of inertia. This one clearly has existed long enough that no one has challenged it as being illogical.

Some examples of bad rule later changed? The one year (or was it two?) ASA called it interference if a retired batter drew a throw from the catcher on a D3K when not a batter-runner. The several years NCAA made it an illegal pitch if the pitcher's first swing up broke a 90 degree plane over her head.

Now, we could start a whole new thread on what we consider bad rules that still exist. For me:
1) Squaring to bunt without attempting to hit the ball is an attempt to hit the ball if you don't pull back. (NCAA & NFHS)
1a) The resulting spawned belief that pulling back AFTER attempting to contact the ball is NOT an attempt to bunt. (NCAA & NFHS)
2) Batters letting balls dribble into their foot and getting an awarded base. (NCAA & NFHS)
2a) The resulting "taking it for the team" attitude that has injured so many players, and allows batters to take away the inside (and our slot).
3) Steel cleats at any recreational level; yep, include that recreational high school, too, IMO. (ASA & NFHS)
3a) The resulting ACL, MCL, MDL, etc. injuries when the cleat bites, and the female knee ligaments can't handle it.

All of the above, IMO, are far worse for the game than calling the BR stepping back to avoid a tag interference. But, that's just me.

And in every other place on the field, there is the possibility that the runner can be safe by retreating to a base. Not even a remote possibility with a BR

See above.

See, the problem lies with the point that the coaches don't know how to beat this rule. I do.

Amen, Brother. Give that man a beer.