The 5% that don’t wear masks must be ex-pats 
https://www.google.com/amp/s/thethaiger.com/coronavirus/thailand-scores-highest-for-mask-wearing-in-survey-of-asean-nations%3famp
Khaosod English reports that the survey examined the habits of citizens from 6 ASEAN member-states and found that 95% of Thais always wear a face mask in public.

https://www.google.com/amp/s/thethaiger.com/coronavirus/thailand-scores-highest-for-mask-wearing-in-survey-of-asean-nations%3famp
Khaosod English reports that the survey examined the habits of citizens from 6 ASEAN member-states and found that 95% of Thais always wear a face mask in public.