Here's why:
* Present Continuous: This tense describes an action that is happening now. It uses the present tense of "to be" (are) + the present participle (-ing) of the verb (being used).
* Present Perfect Continuous: This tense describes an action that started in the past and is still continuing. It uses "have/has been" + the present participle (-ing) of the verb.
In the phrase "They are being used," the focus is on the action happening now. It doesn't indicate that the action started in the past and is still ongoing.