Certification
Type certificates and class societies gate what may carry strangers.
Safety is not a feature sticker. It is envelopes, redundancy, training and the willingness to ground a fleet when evidence demands it.
Redundancy
Spare paths for control, power and braking buy time when one system fails.
Human factors
Fatigue, interfaces and procedures cause more drama than brochure speeds.
Maintenance culture
Inspection intervals and honest logging keep metal airworthy and roadworthy.
Operational rules
Airspace, traffic law and COLREGs exist because physics alone is not enough.