For "driver has fallen asleep with foot on the accelerator pedal", stopping the car might be a better solution.

Not really. Wind down the window; play music loud; vibrate the seat or steering wheel; a strident bonging sound; all would be preferable to bringing the car to a sudden halt in the middle of a motorway.

If an undef in a variable would led you to deleting every row in a database table, it might be better for the uninitialized warning to be fatal.

It's hard for me to imagine how that would occur, but if it is a possibility, then I might resort to use warnings FATAL => 'uninitialized'; within some limited scope(s); but never FATAL => 'all'.

I routinely eliminate/guard against all warnings in my code as I go along; but when they do occur unexpectedly, seeing whether they are 1-offs or repeated, whether once they start, they persist or are occasional transients; and where the code goes and what other knock-on warnings arise as a result; all assist in the postmortem of working out what went wrong and what to do about it.

Even more so when, for example, you get an unhandled transient warning induced by bad data in a long-running, unattended process.