Well then restrict the analysis to modern time when labs have existed. How many pandemics since labs have existed have been the result of leaks before Covid? If the answer is that more pandemics have been the result of lab leaks as opposed to natural causes, then I would lean toward lab leak being the default assumption for Covid. But if some overwhelming fraction of the pandemics in modern times were due to natural causes, I would have to choose natural causes to be the default assumption. The proximity to a lab is interesting, but to understand how to weigh that factor it might be useful to know how close labs were to the epicenters of other pandemics that had turned out to have a natural cause. Mere proximity of one thing to the source of an event is an interesting clue, but it can't tell us much on its own. This could have been a coincidence or it could have been causal. To me, it certainly wouldn't weigh heavily in the face of overwhelming evidence that pandemics are natural events that occur from time to time.
It's like trying to blame an earthquake on a dance party that happened in proximity to the fault line. Okay, maybe, but are dance parties known to cause earthquakes? Do earth quakes happen absent dance parties? Can a dance party theoretically cause an earthquake? I'm not sure, maybe if it were vigorous enough. But if all you've got proximity and a narrative about how it could have happened, without any other proof, then I'm going to default with what I know about pandemics -- they just happen, and so did Covid. I also don't have any proof and just a narrative, but I am reassured by examples of naturally occurring pandemics in the past, and a dearth of lab-leak caused pandemics. I don't see any reason it couldn't be a lab leak, and could easily be convinced with hard evidence. But again, this thread was about default assumptions absent evidence.
It is also about doing dangerous research in imperfect conditions with no oversight, shady behavior like moving the dataset offline, hiding the testing status of kab members, or how the sister lab changed locations to move right next door to the wet market in fall.
It is also about how sars-cov-2 is unique in being the only beta coronavirus with a furin cleavage site, which allows it to be more infectious. It is also a coincidence to that in 2018 Wuhan was part of a failed grant to collect coronavirus in the wild and put furin cleavage sites on them. Failed grant sure, but everyone who works in academia knows that you start working on a grant for preliminary results even before it is filed. And who knows, maybe China funded this dangerous research.
The only problem in all this is how lab-leak was declared to be a settled conspiracy last year. And the only reason was because an orange idiot vouched for it.
How you can compare the history of humanity to the last ten years, the time when we really have started such experiments, is beyond understanding.