It's a country with 20% of the population of the USA. That's not exactly a tiny country.

> If the EU or US were proposing such a law, you should take it seriously

Judging from a few quick searches, there are more Facebook employees in the UK than in Ireland which is their main base of EU operations. They also have a presence in Switzerland (also not EU). FB apparently have some employees in Germany to comply with local hate speech laws, do marketing and HR work, but it doesn't seem like anything they'd miss much if they had to exit especially as they're laying people off anyway.

Now that said, I think Meta can win against the UK govt if they want to duke it out but the idea that the UK is a "tiny country" vs the EU is not reflective of Meta's actual exposure. The EU is not a particularly attractive place for tech firms to hire.