I think this makes a lot of people very uncomfortable, because a lot of people dislike ambiguity—not in the interpersonal sense that might elude an autistic person, but rather an ambiguity of outcomes.
We can’t possible know how everyone would do this or that under anarchism, because conditions and people are constantly evolving. What might make sense to some people in some place and time might not work for someone else, or might evolve as conditions evolve, or might change as people negotiate and compromise with each other.
The allure of systematic and predictable answers is deeply attractive to a lot of people, from ancaps with their natural law deontology to the high modernists who bulldozed cities to make orderly grids of highways to the techbros who think they can engineer their way to eternal perfection. Lots of people want one singular, predictable, replicable Answer and are horrified at the thought of not knowing the results of a social negotiation.