in and out of Bangkok same day - travel restrictions?

[h3ith]

In July, I'll have to go from my province to Bangkok, for some hours of governmental bureaucracy.

Assuming that the situation remains as earlier in June, i.e. no lockdown of all roads in and out of Bangkok:

I'm hearing from Thai acquaintances that if you don't stay overnight in a dark red zone but arrive and leave the zone within some hours (like delivery drivers), you don't have to go into home isolation for 14 days when you return to your home province. 

Did any of you see a more official source for this interpretation, regarding "transit through dark red zones"?

(always assuming that roadblocks don't pop up around Bangkok, some weeks from now)