Canada, Australia, SK, UK, Germany, France, Poland, and Singapore have middling-to-great tech resources, but not the resources to take down global access to the 3 biggest companies in the world.
Only 3 countries have the resources for that: the US, Russia, and China.
I'm super curious why you think that? A 17 year old from Florida tweeted as Elon Musk, Bill Gates or Barack Obama. Why couldn't the Canadian government do it?
Obtaining Admin access on Twitter probably can't take down Twitter. Although, an admin might be able to run heavy tasks that a normal user can't access to DOS the service. That hypothetical would be even easier for sysadmin's to track down though since I believe only a single admin account was compromised.
It was an anecdote. If a 17 year old can socially engineer twitter, I don't think it's crazy to think that a room of comp sci PhDs in South Korea couldn't figure out how to mess with infrastructure, in fact I'm quite sure they could. There are not 3 countries in the world who could cause this type of outage, there are many.
Do we know a lot about Apple's internal reliability/security engineering? Google writes books about it and has things like Project Zero. Windows is used by governments everywhere and so Microsoft probably has some contacts in high places. I have never heard anything about Apple.
True. But a botnet large enough to take down Microsoft, Apple, and Google without being detected would have to be extremely large or well-hidden, so if it is a botnet, then it's even stronger evidence of a state actor.
And yet many such botnets exist and are actively attacking all day long, yet aren't taking down the major professional services outside of tiny temporary corners.
Only 3 countries have the resources for that: the US, Russia, and China.