How Democrats In Chicago Couldn't Rely on Mail-in Voting

Chicago has automatic and permanent mail in voting, so how did the moderate democrat beat the far left candidate 10 whole days after primary Election Day?

https://web.archive.org/web/20240330013553/https://chicago.suntimes.com/elections/2024/03/29/cook-county-states-attorney-primary-eileen-oneill-burke-clayton-harris

https://www.msn.com/en-us/news/crime/man-tried-to-assault-threw-liquid-at-cook-county-states-attorney-kim-foxx-records-show/ar-BB1oKYj3