Which stats say different? I don’t recognise your characterisation of the UK as a particularly racist place, I pretty much never hear racist attitudes experessed in public or private.
The article you linked to didn’t show any comparison country to country so other than anecdote I don’t know on what basis you place the USA and UK as more racist than South Africa. Where do you think any those countries sit on the world stage?
This study suggests this isn’t the case in at least one key metric and South Africa appears to be much worse than either the USA or the UK.