Determining an ASIL involves many variables and requires engineers to make assumptions. For example, even if a component is hypothetically “uncontrollable” (C3) and likely to cause “life-threatening/fatal injuries” (S3) if it malfunctions, it could still be classified as ASIL A (low risk) simply because there’s a low probability of exposure (E1) to the hazard.
ASIL definitions are informative rather than prescriptive, so they leave room for interpretation. A lot of room. ASIL vocabulary relies on adverbs (usually, likely, probably, unlikely). Does “usually” avoiding injury mean 60% of the time or 90% of the time? Is the probability of exposure to black ice the same in Tahiti as it is in Canada? And what about traffic density? Rush hour in Los Angeles vs. late morning on an empty stretch of road in the Australian Outback?
Simply put, ASIL classification depends on context and interpretation.