Yes, took me months to see that too! The point of the chances is though, with some problems you don’t need a definitive answer. Having a solution that solves 95% of your problem can be enough for the problems you would use a quantum computer in the first place. In other cases, your chance is somewhere between 99 and 100 percent so you practically still have a definitive answer.

Use cases are generally problems with very large amount of factors that are not feasible to calculate with normal comouters, think about chemical/medicine simulation and logistics optimization or public transport timetables.