Why do most staffing agencies lie?

Just what the title says. They advertise that they are hiring..."hell immediately" as they say. They have you to come in and fill out an application. They they said they will call you. They never call back. If you call them back the next day, the position was somehow filled overnight, or they give you the "its been slow" bullshit excuse. What pisses me off is that after they wasted youre time, they still have youre information. Its like thats all they wanted is youre information. Im in need of a job quickly, and this has been happening too much, what should i do?

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