Yes, artificial monopoly is the major issue here.
With respect to the "$99" annual fee, the issue is that it isn't a good deal at all when a developer wants to offer the software for free - most open source developers don't even collect any donation, and it is doubtful if many of them can even raise $99 every year.
This is where regulation is definitely needed - big tech should not be able to force us to pay and use only their signing infrastructure, and government law should require any CA to stringently implement KYC (know your customer) norms, like banks do, before issuing certificates to any Tom, Dick or Harry.
I would preferably like to see the end of such "App Store" nonsense, but would gladly compromise and accept it if there is no monopoly (with the caveat that side loading / direct installation of apps should not be restricted - nobody should be forced to use an "App Store" if they don't want to).
(App Store is so successful on ios only because side loading / direct installation is restricted on it).