Tipping in others countries can be a problem for some visitors. In S.E. Asia it should be no problem at all. It is not expected anywhere as a general rule and it is most certainly not compulsory. In certain favorite places I will tip as I know the locals and they give me excellent food and service. These are only restaurants for tourists though.
In 22 years I have never tipped in a locals only restaurant. I once told a lady to keep the 5 baht (20 cents) change but she chased me down the street to give it back to me. If i have one major gripe with certain tour operators it is charging customers up front with a “compulsory” tipping charge prior to starting a tour. Tipping made easy is what they call it among other rip off names. I call it exploitation in many cases. Locals will be paid by tips only in some cases. $10.00 a day per person on a 2 week tour in this region is totally outrageous. This is purely an extra tax on your holiday costs. Because westerners have started a culture of tipping some places now hope for tips and when given they are much appreciated as anywhere in the world. But no one will ever expect a tip. Your Baktrax tour coordinator will always offer advice on local protocol and cultural norms.
In some better class local bars where locals sit at tables drinking there are often barmaids who hover around the tables immediately mixing whiskey drinks on a continual basis as soon as a glass is empty. Likewise even when you take a mouthful of beer they will immediately top up the glass from your bottle. This is Thai culture only and at the end of the night the locals would tip them. Most westerners do not even want or like this service and will make that clear. But even a tip without the service would be much appreciated in this situation although no problem either way.
So the bottom line is always; IT IS TOTALLY UP TO YOU ON ALL OCCASIONS . Nothing or as much as you want but never feel obliged/guilty/embarrassed whichever way you go. Try the following tour to experience different cultural norms among real locals only.