Read exclusions. Some exclude what you want covered.
A coworker bought a Lexus for wife, extended warranty. Car smelled moldy. A/C condensation drain cracked, known Lexus issue covered under regular warranty normally. Car was out of regular warranty and extended warranty specifically excluded it. He paid for the $2000 repair and got them later with a valve train noise.
BMW dealer told me clutch slave cylinders sometimes excluded.
Someone should sell final drive insurance. Say $50 per year, I bet 90% of us would buy it and the real number of failures could be revealed.