I am a UK non tax resident, I do not pay tax to the UK on ANY of my earnings regardless of where I earn it. If I spent more than 183 days in Thailand I would be liable for Thai tax.
that’s not true. You are liable to pay tax where you are resident first, then under some countries laws you are also liable for any shortfall that you would have paid in the country where you were paid and/or are a citizen of. This is the case for Americans I believe. Tax exiles don’t pay tax where they earn money, they pay little or no tax in the country they reside in, hence an exile.