An open-entry trade show floor fills the moment the doors unlock. A registration-and-confirmation conference floor never quite crowds - it fills slow, over the whole first hour.
That difference has nothing to do with the attendees. At the open-entry show, anyone with a walk-up pass gets in - no cost, no confirmation, no moment where backing out would have been easier than showing up. At the conference with mandatory registration, every person on that floor already cleared three separate points where dropping out was the easy option: registering, paying or getting approved, and confirming days before the show.
The organizer already qualified that room before you set up your booth.
I have watched reps run the identical booth script at both kinds of floors and then wonder why the open-entry list looks worse in the CRM the next morning. The script was fine. The floor was not the same floor.
The same survey question - "are you evaluating a new vendor this quarter" - carries a different base rate of truth depending on which door the attendee walked through. On an open floor, plenty of people answer yes because it feels like the polite thing to say to a rep who just handed them water. On a confirmed floor, the people saying yes already spent money and time off getting there.
A free floor gives you reach. A confirmed floor gives you a head start on the qualifying question.
High footfall from an open-entry show is not wasted reach. It becomes wasted only when the booth runs the same qualification bar it would run at a confirmed conference, expecting a door that never did the work.
Most teams read one footfall number off both floors and draw one conclusion about the show. The floors were never the same show.