What are the airport and hotel testing procedures for travelers arriving in Thailand?

So, my approved hotel says I must get a test at the airport. OK I've booked and paid for this, but the emabasy says,

The testing is conducted at hotels, where travelers are required to stay until the result comes back. The amount of time needed varies, some report a waiting time of just six hours, while others say they had to wait for a day and a half. So what is going on. How is this even possible.