When Algeria was French performing nuclear tests there in the Sahara was not much different from the US performing nuclear tests in Nevada/New Mexico. The British performed tests in Australia for the same reason.

It was not a question of 'caring' but simply that it was sufficiently big and empty while still being accessible to be deemed an acceptable option taking into account that having nukes was a top strategic priority for national security.

As it happens nuclear tests continued in the Sahara even after Algerian independence under an agreement with the new independent Algerian government (so clearly they did not not 'care much' either) before they were transferred to the next possible location... French Polynesia.

It should also be noted that the British and the Americans had already carried out nuclear tests in the Pacific when the French moved theirs there as well.