That still makes for a bear minimum of 50 people eligible on any given day-- maybe some days have up to 150 eligible folks (HKG-ORD is really GS-heavy on Fridays, for example).
Bear in mind the setting of ORD Arrivals is completely different with SFO Arrivals. ORD Arrivals is after security, or I should say way pass security at concourse C rather than B. SFO Arrivals is outside security. Therefore even there are pax eligible for Arrvials in ORD, they can't take advantage of the facility if they terminate in ORD, or have flights other than UA. or their UA flights leave from B gates ( I never saw anywhere on ORD about signs for the Arrivals, it is too much to walk to C and back to B just for a shower) unlike the convenience of SFO Arrivals just right after the immigration. I can tell you there are never more than 20 people inside the Arrivals in ORD on any given days.