Fly by wire has been around for a very long time, early analog systems notably by Dassault, were introduced over 50 years ago. NASA first tested digital fly by wire in the early 1970's.
Tens of millions of hours have been logged with no evidence of any systemic problems....and you are kidding yourself if you think contol cable/hydraulic systems don't fail....they can, and do, but thankfully not regularly.
All aspects of travel have some risk..but with aviation it's probably the drive to the airport that will kill you rather than some oddball systems failure.
As for cars...many modern automobile sub systems have similar technology. Notably Mercedes S and E class models. They work superbly.
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