Either you've never actually built anything worthwhile or your sentiment approaches the people who say "I never trust anyone" without thinking about what that statement actually means.
Car companies lay their fate of their passengers in third party tire companies and third party brake companies.
Airplane companies lay their product's fate in the hands of third party engines.
Airplane passengers lay their fate utterly in the hands of some third party pilot.
Car drivers lay their fate in car companies and other drivers.
Spreadsheets? Data? Whatever works best right now will do 99.9% of the time.
Yes, clearly every social interaction is based on some level of trust. Your examples sort of state the obvious.
The point is, I will not drive on shitty tires if I have a reasonable option of good ones. I will not knowingly fly with a drunk pilot if a sober one is available.
Airbus - and nearly everyone I know - happily hand over ultimate control of their data trove to someone else, seemingly without any pressing grounds for doing so.
And yes, I know that is the way of the world these days, however much I may bemoan it. Witness the snide and micro-agression even here on HN whenever someone dares to differ.
Car companies lay their fate of their passengers in third party tire companies and third party brake companies.
Airplane companies lay their product's fate in the hands of third party engines.
Airplane passengers lay their fate utterly in the hands of some third party pilot.
Car drivers lay their fate in car companies and other drivers.
Spreadsheets? Data? Whatever works best right now will do 99.9% of the time.