You get what you pay for:

I served as a public defender for nine years, and the old adage is true: "You get what you pay for."

The public defender's ultimate pragmatism is directed toward his or her paymaster, in other words, the government, not toward you.

While there are very good and very talented public defenders, many truly concerned for their clients, there is no way to guarantee loyalty.  Even if your public defender is committed to you, with a stroke of a pen (or now, a collection of electrons), your public defender can be removed by his or her supervisor from your case and transferred to other clients, other jurisdictions, other courts.  I know: it happened to me multiple times during my tenure as a public defender.

To ensure loyalty to you, always, always, expend the money necessary to secure a private defense attorney.