If I've understood everything correctly, the cause of several mishaps has related to blocked pitot tubes.
why does flying safely rely on something that is obviously liable to blockages or damage?
This being the question (and not your presumed answer)
My answer is that
Flying safely does not rely on something that is obviously liable to blackages or damage?
The failure condition is anticipated and safe aircraft operation is assured by virtue of backup systems and pilot training. Most of the problems occur (unsafe flying) when the pilot becomes confused and fails to employ the backup systems and operating technique.
I'm afraid that even adding additional systems would still not assure safe flying if the pilot didn't understand what was happening and failed to use the backup system correctly.