At which point you would be threatened with a trial that might not even be that winnable by the prosecution, but that they'd use as a stick to bully you into taking some kind of plea bargain, maybe even without jail time, but now at least you're on probation and/or have a criminal record.
In this particular case, if she had pulled the whole "I don't give consent to search anything", "Am I being detained", "I want my lawyer" bit, she most likely would have been searched anyways, had the possession charge filed, and been convicted of it, no matter what kind of lawyer she had, because there were in fact drugs in her car. On the other hand, engaging with the officer and behaving in a way he would expect somebody who is actually innocent to behave allowed him to take a closer look at things and decide that the evidence doesn't quite match up with an open-and-shut possession case, and that it deserved being looked into further.
That's not to say this is a good idea in every situation. The lawyer advice often is a good option, particularly if you are in fact guilty of the crime that you are suspected of.