In the early 2000s, the EPA released a study that showed 85% of commercial buildings had sustained water damage at some point, 45% of which had existing leaks.
While there hasn’t been a similarly deep study of commercial water damage, you can bet that the situation hasn’t changed much. Minor roof leaking is often seen as low priority—an annoyance that can be dealt with at a later time.
However, you can’t just wait until leaks become apparent on the interior. Anything from improperly-secured RTUs to roof penetration, extreme weather, excessive foot traffic, materials/membrane/sealant failure, improper inspection and beyond can cause leak-inducing damage.