Why does the progressive insurance want my mother's copy of her social security number and license?

So my uncle is putting me on his car insurance so I can drive his car. I am 17 they asked for my mom's signature I understand that part because I am a minor and need tge parental cinsent but they asked for a copy of her SSN and license. Why? Shouldn't they be asking me for mines since I'm the one driving. I don't want her to go through unnecessary problems.

If they do charge her why would they charge her with anything if its my uncles insurance and I am the one getting put on it not her?