Its dead simple because other services seem to have figured this out. Twitter does actual real time systems, and its not 1-to-1. Slack meanwhile seems to have no trouble delivering me messages. iMessage however is the outlier here, maybe because they don't live and die on this system like the others I mentioned. If you're going to make a new system to replace the old one (text messages), make sure it works first.
2. The comparison is because it is a strictly easier problem and they still do strictly worse. If you want to compare Apple Online Store to Amazon Online Store, the report card is equally bad: imagine if every time Amazon added a new major product they took the ENTIRE STORE DOWN FOR HOURS.
3. It seems to me that iCloud is the thing that is more like "just a drive". Google has Photos, Calendars, and email too, so I'm not sure what you're referring to with all this Google comparison. 5GB is kind of nothing when we start talking photos and email, and Google actually does cool stuff with my Photos, and Dropbox still hilariously feels more integrated with the OS than iCloud, not to mention having integration with other services.
The truth of the matter is that they do bare minimum on all their services, which is FINE btw -- just absurd to claim they have any special competence in the area. Nothing about their services stands out, with each one its literally one step above nothing which would be unacceptable. With email they NEED some basic email to give you with your devices. With the App Store they NEED some way for you to get apps. With the online store they NEED some way for you to order products.
Now compare Apple to Apple (ha): look at their absolutely, everyone agrees, stellar physical stores. Thats something to write home about. Look at their amazing supply chain where they can replace or fix a phone in hours -- truly surprising every time I go in. This is something they have clear core competency in.