Modern cars are vastly safer. Demonstrably so.

Computers in cars may make them more dangerous. But this is far outweighed by the greater overall safety in the cars that have them. You can't buy an otherwise modern car with no computer control, so your choice is either to buy a modern car with computers, or buy an old car without them. If you're avoiding computers then you're buying an old car, and the result is greatly decreased safety.

This is typical human risk management, of course. The mostly imaginary scenario where your ECU goes nuts and causes you to crash helplessly into a concrete barrier is assigned great importance, where the sadly common scenario of some drunk or texting (or drunk texting) idiot killing you in an accident that modern safety design would have allowed you to walk away from is assigned very little importance.

It's much like people who are afraid of flying but are happy to drive, because the thought of plummeting to their death from 30,000 feet is much more vivid than the thought of being randomly run over by a tractor trailer even though the latter is much more likely.