I disagree with the assertion that this happens all the time in Division I college softball ... In fact it is uncommon.
Please review the number of verbal commits dropped by Alabama, Oklahoma, Michigan, and Washington over the last five years (elite programs with little to no changes in staff). The number is very, very low. Michigan hasn't dropped a verbal in more than a decade (or longer).
Drops in verbals are almost always due to a change in coaching staff or violation of the agreed upon stipulations (maintaining certain gpa, staying out of legal trouble, commitment to strength and conditioning, etc.).
Let me reiterate - coaches dropping verbals is not the norm by any stretch of the imagination. Will this change? Maybe. But currently I would guess that it is not even 5-7% of all verbals get dropped by coaches.
In fact, many dropped verbals come from the player backing out after a coaching change. Note - this is not frowned upon or held against the player.