Your other points are more or less true, I just like to think that people complain a lot and media obviously makes it worse.
Digital health cards, online tax declaration, etc. These things did happen. People complained, but these decisions were not reverted. That's the most important.
By many things at once: Datenschutz, (over- and premature) regulations, bureaucracy, laws favoring old ways (e.g. broadcasting licenses for streamers), active sabotage from workers who don't want to learn things (and can't be fired) etc.
But all stems from risk averseness and active unwillingness to learn new ways.
As you say, (some) things did happened, but way too slow and way too little. Compared to its peers or especially developing countries German Digitalisierung is a joke, a not so funny one.