It's really optimistic to think mass rollout of Apple/Google protocol wouldn't be abused. Once government makes it compulsory to use such app in some scenarios (and society actually agrees to do that instead of protesting it en masse) it's over. There's nothing fundamentally stopping government from later changing the technical mechanism ("Please install our national app; it's more trustworthy than foreign megacorps"). Good percentage of society is not technical literate enough to differentiate between "brilliant Bluetooth solution" and "dumber contact tracing relying on data brokers"; for many people that's just implementation detail on the same level as new UI.
Can't wait until few years down we learn this data has been abused to harass political opponents in some way. Or when someone runs experiment to pull everyone's data and use ML to predict crimes (Minority Report style). It's done, we are never escaping the "sanitary" regime (just as we never got back to world pre-2001 despite extensive war on terror).
And how would you know if there was a backdoor that allows the government to pull anyone's data? Even if the app is validated by reliable third party in current version, there's no mechanism stopping a malicious update in few months.
Once it's mandatory to have such app it's game over. Doesn't matter what algorithm is being used, doesn't matter who developed it. It's insanely easy to abuse this. The government will simply deny there's any sort of backdoor and gaslight people who say otherwise.
I'm not saying he wants kids to die young, please don't strawman me. I think Gates career as CEO points into direction he enjoys acquiring and wielding power. He stepped down from being CEO in 2008, this was long after Windows won. It's also possible that he enjoys both technical side of challenges and being powerful at the same time.
I'm not convinced if Gates actually cares about the world. I find his transformation from one of the disliked CEOs of most despised companies into some sort of high tech messiah hard to believe. The phrase "Embrace, Extend, Extinguish" was coined in Microsoft when he was the CEO. Google bombing was invented to redirect to Microsoft homepage when searching "more evil than satan himself". Those are facts that confirm the sentiment I remember.
In my opinion, his philanthropy work is just another playground. Power is addictive and now he has way to exercise power over world outside the tech industry. Quick Google search shows he spent 45B$ on his foundation... and another search shows his net worth is still 119B$. This is still more money that I can imagine, even if he spent 99.9% of it he would still be richer than I can ever hope for. And honestly, his personal brand is so strong that even after zeroing on his account balance he could become multimillionaire in no time.
Maybe I'm overly cynical. Maybe my memory fails me and I'm mistaken about how bad reputation he and his company had back in the day. But it's hard for me to buy this 180 degree turn from ruthless CEO into great philanthropist. Now, I'm not saying his antichrist and he planned the pandemic 20 years ahead; I just would appreciate some healthy skepticism.