Re: a complaint that affects a large number of customers at once
"There is no way of making a complaint that affects a large number of customers at once, it relies on individuals, each making their own complaint."
Not really true. Not for the last decade or more in the UK anyway:
https://www.gov.uk/government/publications/what-are-super-complaints/what-are-super-complaints
But other than that, your general points are valid.
One important point you miss is that the people in charge of messes like this ensure that they are personally and individually very well rewarded when the organisation/business "does well" (according to some benchmark), and yet somehow are not personally and individually responsible when the business does badly (e.g. lets down the people who pay for the organisation). How does that work?
Fix that basic principle, and a lot of generic corporate megaproblems and megacomplaints will magically disappear without too much further intervention.