Either they were not interested in introducing their movements into Israel or, while recognizing the utility of those movements for their own situation in America, did not view them as "authentic Judaism" and hence saw no good purpose being served by having them introduced into the Jewish state.The few efforts that were made failed because movements resting on voluntary funding could not attract enough people willing to support such efforts in Israel.Indeed, the only Reform Jews were a few refugees from 1930's Germany who had brought German Reform with them and had two congregations, one in Jerusalem and one in Haifa.There were no Conservative congregations since the Jeshurun Synagogue, which had been established in the 1920s with half an eye to becoming a Conservative congregation at a time when the distance between Conservative and Orthodox Judaism was minimal, had long since been absorbed into standard Israeli modern Orthodoxy.The issue of who could perform weddings and conduct conversions began to emerge but it was still possible to deal with those issues in informal ways without confrontations.The Chief Rabbinate granted selective permission to the more halakhically learned Conservative rabbis to perform weddings in Israel and others found ways to work jointly with recognized Orthodox rabbis, since officiating was not the halakhic problem but witnessing.
Worse than that, an objective observer would probably also have to agree that both are right, at least in some ways.
It was only two decades later with the arrival of the mass aliya from the Soviet Union and then former Soviet Union which included many half-Jews who claimed to be Jews but could not meet the halakhic criteria that the issue became a real one for Israel as well as the diaspora.
At the same time, Reform and Conservative pressure for recognition was stepped up.
It was only after the Six-Day War that small but meaningful groups of Conservative and Reform Jews settled in Israel as olim and established congregations and local institutions, partly for themselves and partly to establish a movement presence in Israel.
The Reform movement, which was beginning to make a greater international effort at that time, even established its international headquarters in Jerusalem.