Ask HN: Why does every country needs its own Covid contact tracing app?

Several countries have now launched contract tracing apps, with other countries, like the UK, marred by overspend and delay in launching their own. If many of these are based on Google and Apple contract tracing protocols, why is there a need to develop an app per country? I could see benefits of skinning the apps and maybe links/email to local health advice, but over and above that, it seems really wasteful, and with delays, will have a real human cost.