I don’t interpret what the government or pharmaceutical companies have said as ever claiming these things are literally 100%. If I tell someone that (Pulling these numbers out of thin air!) ‘for this vaccine if given to a population of 10 million people, 10 it will kill, 15 it will cripple, 100 it will do nothing’. So your chance of a non-positive result is .0000125. Very few people would have a problem with releasing that vaccine unless they’re one of that .0000125 and then only if harms them. (Actually the bad stats are probably way too high to ever release that vaccine! I don’t really know!) Most people (including government people!) would say its perfectly safe. It is perfect - 100% . It’s not! But it will be interpreted that way by 99.99999% of the people listening.
Then when the “defect” occurs, the actual facts are forgotten (if ever learned !) and politicians and other demagogues make hay!!
The government also has for 75 years or so told everyone social security is a retirement plan & not a Ponzi scheme. A lot of people on this site believe the retirement plan claim!