Cases that the Commonwealth are not ready to proceed on on the day of trial can be dismissed upon motion by either side. Sometimes if the victims fail to appear and the Commonwealth asks for a continuance, the judge may grant the continuance and not dismiss the case.
A case can also be dismissed prior to the day of trial, either upon motion my the Commonwealth or upon motion by the defendant. If the Commonwealth moves to dismiss, the judge usually allows the motion if the defendant does not object to the dismissal. If it is the defendant who moves to dismiss, the defendant must convince the judge to dismiss the charge(s) by citing some legal reason why the charge should be dismissed, for example a lack of probable cause for the complaint to have issued in the first place or as a sanction for non-compliance with a court order by the prosecutor.
Since every case has its own set of facts, different lawyers with different skills and reputations, and judges, who also have their own idiosyncracies, it is impossible to apply one favorable outcome to every other similar situation. Typically, if a victim or critical witness doesn't show up and the defense lawyer asks for dismissal, the judge will usually allow the prosecution at least one additional opportunity to have the victim/witness summonsed in. If this has already happened once or twice, or if it is clear for some reason that the victim/witness will not likely be showing up in the future, the judge will allow a defendant's motion to dismiss. Keep in mind that the victim/witness' appearance is only required or needed at trial or particular court events. Therefore the absence of a victim/witness at the first pretrial conference is unlikely to support a defendant's motion to dismiss.
This point really emphasizes why it is so important to get the best criminal defense attorney that you can afford in every situation. A more seasoned attorney is more likely to know how to set up the appropriate situation (right judge, prosecutor, court event, etc.) to make the dismissal more likely. Also, a District Attorney is more likely to agree to dismiss if he or she knows that your attorney is likely to beat the case anyway. So again, an attorney with a stronger reputation in that particular court will fare better than a less experienced and less known counterpart.
It was a public defender who got the job done in the case you viewed and there are many extrememly good public defenders out there. The problem is that you don't get to choose. Always get the best lawyer you can afford. It will be well worth it in the long run.