As a developer in Chicago, I think it's because the finance sector sucks up a lot of the talent, and it's less known for marquee non-finance companies. The city has struggled to promote our tech scene.
The company I work for participates in UIUC's City Scholars program[0]. If you work for a company in Chicago, push for them to participate. It introduces the students to Chicago's tech scene.
To add to your point, I was made aware of a tech role at a financial firm in downtown Chicago (dev, infra, and infosec experience required); $300k-$400k total comp. Can't compete against that if you're in Chicago and only sourcing Chicago talent.
The company I work for participates in UIUC's City Scholars program[0]. If you work for a company in Chicago, push for them to participate. It introduces the students to Chicago's tech scene.
0: https://cityscholars.engineering.illinois.edu/