Why Can’t British People Speak Two Types of English?

Is it possible for Scousers/Brummies et al to speak two types of English – one colloquial with a strong accent when conversing locally with fellow inhabitants of their area, and a separate clearer non-accented English spoken when conversing with the rest of the country? Article by TP Transcription Limited.

https://www.tptranscription.co.uk/why-cant-people-from-liverpool-speak-with-a-clear-english-accent/