Following are the quality assurance examples in real time scenarios.
Customer reports of a car manufacturing company are received by a quality assurance company. Responsible quality assurance company investigates the report and  finds the root cause of the issue that the customer is facing. The software team works on it and develops the fix for the issue. Quality assurance companies make sure that customers update their software using a free toolkit.
A bank faces issues regarding double transactions in customers' accounts. Quality assurance company investigates the case to find out that more than 20000 transactions have been executed twice. The responsible quality assurance company submits a report to the IT team to prevent recurrence of events. They checked the system to find out why the reconciliation system did not provide warning of this bug and do the needful to optimize IT controls.