I think that's more of an auxiliary issue than the "fundamental" one. Space is limited, and a nice (and non-collapsing) bridge could be more convenient for pedestrians than however things would be laid out on the ground even if there wasn't a road there. Safe bridges should be able to exist, whether one would have been needed in this exact spot in an alternate reality or not.

It's also very telling for you to condense "a freeway and a gigantic parking lot" down to "one single driver ever." Five motorists wouldn't have been killed by the collapse alone if "one single driver" was the only one who ever used it.