It is relevant. If (giving an extreme example to make the point), statistically two humans were killed servicing airbags for every life saved by airbags, cars wouldn’t have airbags (with possible exceptions for cars of the super rich and super important such as the POTUS)
Also, an escape system adds weight to a rocket. That weight could be used for other stuff that makes the rest of the system more reliable (slightly stronger fuel tanks, redundant pumps, whatever). Designing the escape system also takes resources away that could be used to improve the safety of the primary system.
For rockets, it’s not easy to decide what’s the best choice; we launch too few of them, and the ones we launch change too often to gather reliable statistics. Getting real-world data on the reliability of escape systems definitely is hard, as it requires numerous rocket failures or elaborate test setups (a full test must include high speed and an explosion that may throw material through the engine of the escape capsule)