Apple has a pretty good reputation for security. IOS does not suffer from many of the architectural issues of its rivals, and high profile cases of law enforcement being unable to access the locked iPhones of felons (with Apple resisting legal challenges to build backdoors) has certainly helped their image.
Perhaps this good standing is why in the case of the recent Facetime group-calling flaw the company wasn't listening to its users. Tech organisations should always have channels open for customers to report issues, with processes to escalate those affecting security to suitably qualified teams. Apple has since apologized and agreed to reward the 14 year old boy who discovered the issue, but it seems that some among the independent security expert community are still sitting on Apple vulnerabilities because they don't get paid for finding them. Their calls for a bug bounty aren't unreasonable given that otherwise there would be no incentive for them to probe for flaws in Apple products.