Most currently non-Thai passengers flying into Thailand can't do the mandatory 14-day quarantine at home.
From https://mobile.twitter.com/RichardBarrow/status/1268924407537233920 (mirror 1, mirror 2):
Q2: If I fly to Thailand, can I quarantine in my own house or do state quarantine for free?
A: No, for the foreseeable future, foreigners must book a stay in Alternative State Quarantine for 14-days at their own expense. These hotels will cost you between 32,000 and 60,000 Baht.
However, https://mobile.twitter.com/RichardBarrow/status/1282687924484497409 (mirror) and https://www.bangkokpost.com/thailand/general/1950708 (mirror) mention some exceptions:
“Diplomat families are required to self-isolate at embassies or residences for 14 days and up until now there were no problems. The CCSA will rethink its measures to make them more comprehensive,” said Dr Taweesilp.
I don't know whether Thai passengers can quarantine at home. I believe most, if not all, can't.