The reason is the Kol Nidre.
"When, on the Day of Atonement, you walk into a synagogue, the very first prayer that you recite, you stand -- and it's the only prayer for which you stand -- and you repeat three times a short prayer. The Kol Nidre. In that prayer, you enter into an agreement with God Almighty that any oath, vow, or pledge that you may make during the next twelve months -- any oath, vow or pledge that you may take during the next twelve months shall be null and void.
The oath shall not be an oath; the vow shall not be a vow; the pledge shall not be a pledge. They shall have no force and effect, and so forth and so on.
And further than that, the Talmud teaches: "Don't forget -- whenever you take an oath, vow, and pledge -- remember the Kol Nidre prayer that you recited on the Day of Atonement, and that exempts you from fulfilling that."
That explains a lot, doesn't it, readers?
Israel rarely honors agreements
"Israel has signed a series of binding agreements to freeze settlement activity, which it never intended to fulfill. Of the 40 years of occupation, only during three has construction been stopped despite all the agreements and promises to do so. There is no reason to believe that Israel will behave differently this time.
Of all Israel's iniquities in the occupied territories - the brutality, the assassinations, the siege, the hunger, the blackouts, the checkpoints and the mass arrests - nothing serves as witness to its real intentions than the settlements. Certainly for the future. Every home built in the territories, every light pole and every road are like a thousand witnesses: Israel does not want peace; Israel wants occupation. Whoever is serious about peace and a Palestinian state does not put up even a shed.
From Oslo through Camp David and on to the road map, Israel has not put an end to the most criminal enterprise in its history.... This terrible enterprise, whose purpose is to foil any chance for peace, is also a criminal enterprise."
Heads I Win, Tails You Lose
"At the beginning of the first intifada, in 1988, Israel expelled Mubarak Awad, a Palestinian-American child psychologist who advocated Gandhian tactics for resisting the occupation. The Israeli government understood right away that nonviolent tactics had the potential to embarrass Israel, and was determined to stop him."