Another important distinction is between an “app” and a “protocol”. What Google and Apple are delivering is a protocol, and presumably a central server to receive the reports. They may accompany this by an app, but it will be one among many.
Singapore seems to use something very similar to what Google and Apple are doing, but they’re also storing your phone number when you create an account. And there’s a way for the authorities to deanonymise the people you’ve been in contact with. So it’s not “privacy respecting”, regardless of what they claim (whitepaper here).
Germany has reconsidered and is now also backing the google/Apple scheme.
France is using a scheme that apparently is also not privacy protecting, but I can’t really discern that from the whitepaper. However, the people behind ROBERT have acknowledged this flaw in their response on a Github issue on the subject. I’m not sure whether France will fall in line with the rest of the EU to guarantee interoperability, or whether they’ll dig in their heels and stubbornly continue with their own incompatible implementation. Knowing the French, it could go both ways.
Australia apparently is also doing its own thing, but I haven’t found any details on their implementation in the short time I’m willing to allocate today. It appears to be similar to Singapore’s approach though, and also requires a phone number to create an account, which raises some red flags.
All of these implementations are (or will be) open sourced so the public can inspect them. All of them are, for now, entirely voluntary. And that’s unlikely to change for reasons I’m not going to repeat.
In conclusion: sure, some countries are doing their own thing, and left to their own devices, it appears quite a few of them are bungling it. That’s precisely why Google and Apple are pushing for this: in order to have one standard and secure way of doing this across the globe. Because COVID-19 does not stop at the border. Having one standard way of doing contact tracing is greatly beneficial because it would make the data relevant across borders. Because people actually do cross borders on a regular basis. Google and Apple represent the majority of mobile phone users. That’s why they are in a unique position to push for a unified and privacy respecting approach to contact tracing.