Nassau County, New York is known as one of the toughest and most difficult places to practice in New York and throughout the United States. Plea bargaining is perhaps the most difficult part because all plea bargains in the District Court are basically set by Supervisors and Assistant District Attorneys in the various courtrooms have almost no discretion when asked to reduce a plea offer. Instead, they must get approval from their Supervisors on a regular basis and have almost no autonomy or discretion - unless they can explain why they would even consider departing from the original offer made by the Supervisor and justify their lesser position. This is usually what makes practicing criminal law in Nassau County so difficult because the attorney cannot speak directly with who is "pulling the strings" on most cases.
As a result, when plea bargaining a straight forward type of case would normally take no more than a couple of court appearances in any other county, in Nassau County it could take 4-5 or more appearances to get the same - or a worse outcome.
Worse still, Nassau County is known for being the harshest county on Long Island and most other places in New York state since they refuse to offer much in the way of a plea bargain - unless they have no case to speak of. Then they might just offer you a slight reduction in their offer. As a result, many cases that would be dismissed in other counties are being vigorously pursued in Nassau County to prove they can do it - even though they lose a lot of those very cases they press to trial.
In other words, Nassau County is a good place to stay away from if you intend upon doing any crimes. Perhaps that's why they choose to act that way and perhaps that's the DA's intent.