Software gets used for mission critical things all the time, with the same level of assuredness. What you are complaining about is that people making apps to show you the right advertisement or a website to watch pictures of cats sometimes is buggy and gets deployed without proper tests.
Meanwhile almost every medical device under the sun today has software, nuclear powerplants run on software, space missions use software, airplanes drive themselves and land through software, etc.
Meanwhile almost every medical device under the sun today has software, nuclear powerplants run on software, space missions use software, airplanes drive themselves and land through software, etc.