Do hotels in Thailand booked by travel agencies have wifi?

This depends on whether the hotel above your itinerary provides free wifi service. Of course, some things offer free wifi service, while others don't. Last time, a colleague of mine went to Thailand for six days with a delegation from Youtrace.com Daily, but I couldn't get in touch occasionally. As a result, when I asked the hotel where I stayed, there was no free wifi service. Of course, if you report a higher-end itinerary, there will always be high-end hotels.