Just because there are no fatal crashes linked to maintenance issues recently does not mean everything is hunky dory.
On the day of SWAʻs fatal fan blade incident, Delta and UAL had emergency landings due to maintenance issues.
There are a dozen or so emergency landings a month in the US. Some are pax related, but the majority are maintenance related. Its really not many, but they do happen. The redundancy of systems and pilot training help to alleviate the dangers.