Why do ordinary senators have IMDb page?

They make appearances in feature films or talk shows, and users care enough to give them a credit.

She's not a Senator, she's a Representative.

Anybody, elected officials included, with a television or film credit will have an IMDb page.

Ocasio-Cortez has appeared in many television series, she has on-screen credits for her appearances, an IMDb Contributor created her IMDb page.

She is the main person featured in the documentary Knock Down The House (2019), her name is in the credits, that alone is enough to create her IMDb page.