99.99% is pretty fine from the engineering point of view. The buildings and other constructions surrounds us have about the same theoretical reliability conside

99.99% is pretty fine from the engineering point of view. The buildings and other constructions surrounds us have about the same theoretical reliability considering all the uncertainties involved like weather, load and impacts, long term characteristics, material and manufacturing uncertainties. Of course this centuries long trial and error supported pretty simple science of construction engineering needs to be supported by law level standards and regulations allowing certain low level uncertainty otherwise the 'engineers want to sleep at night' aspect was forcing us to make only very expensive bunkers to live in (or only sociopaths becoming engineers). There is an accepted level of risk involved in engineering. Usually mathematics and (proper) algorithms is the topic where everything is 100% (good quality actually finished work, not an early prototype released as final is assumed). It just may or may not to be fully relevant to our life.