85-90 might seem like a lot to some folks, but it's not at all uncommon for traffic on the highways around Chicago. Personally, I'd much rather a driver get me to where I'm going quickly if it's safe. 80-90 on an open highway isn't a problem, it's the drivers who are constantly switching lines and cutting off other drivers to "get ahead" I have a problem with.
If you're cruising at 90 in cook county you're asking for a court date. 15mph over the limit mandates it, and I think the highest speed limit is 60 on 290 out in Arlington Heights. It's 45 on the Kennedy once you get into the city right now.
I think it’s most likely changes in I-88 since I lived there are responsible for any difference.
In my experience, 80-90 mph would be uncommonly high for either route even on an open highway. It's not the norm until you get out to the far flung suburbs like Naperville (I-88).
The taxi picked us up, proceeded to drive us Downtown and upwards of 85-90mph on the highway (was about 11pm at night at this point). The car was probably at least 15 years old and the shocks nearly as old.
After that experience, we used Uber the rest of the trip (and back to the airport) and it was an overall better experience by far.