Cannot be hundreds of millions of Thais as there are only 68 million total. Many businesses open, restaurants and bars serving food, delivering food through grab, etc... the new normal
It is science and their concern for public health and safety that suggested the lock-downs to the government.
5 million livelihoods have been crushed by deaths of family and friends from Covid 19 as well. You can find another job (livelihood), but you only have one body to live in.
From the Bangkok Post: "Thai nationals who had earlier left Thailand to visit any of the 46 countries, but stayed there less than 21 days will not be quarantined and will not be required to have health insurance cover of $50,000. However, expats who have stayed in one of the 46 countries for less than 21 days will have to provide proof of $50,000 in coverage on their return."