I used to work at a mobile app test automation company and there is an alternative answer: apple is the fucking worst. They used to frequently make additional changes that are not in the beta just before release and other companies have no warning until its live. I remember when ios8 released in between the final beta and general release they ripped out the entire api our platform used to interface with phones. We had to rewrite iOS support from scratch in like a month post release. It was a disaster.