It is true that nearly all airliners are fly-by-wire (fbw) today. Both the electrical and computer networkery is four- or five-times redundant so unlikely that all ten or so systems will fail at once. I believe it is correct that no accidents have been caused by fbw breaking. However, the aviation industry has spent decades and billions of quid getting fbw right. Introduced a little at a time. Checked, double checked in endless test flights.
They would never introduce a new system without extensive testing and a back-up on early systems. But this seems to be exactly what car makers are planning to do with steer-by-wire. If you want proof that automotive digital stuff breaks, just look at those Tesla owners who were recently locked out of, or inside, their vehicles. If a digital door can stop working then so can a steering system. Sadly, our cars are not equipped with zero-zero ejector seats like many test aircraft!