there's a video where we can see Biden tottering along on the very wide sidewalk in front of the hotel. He's entirely alone, no agents or anyone else around them, which seems pretty careless if he's the president. He hears the crash, stands there and gapes at it for s short time, and then - after looking at each other and trying to decide what to do - the agents come over and get him into the car.

Does not look remotely like any USSS or presidential operation that I ever saw. Compare it for what they do for Trump, even when on private property. This incident with Joe's motorcade was in a downtown street.