Just landed in BKK on a fresh DTV, received in Jakarta as a freelancer. I was asked by immigration what I did and asked to show proof of my work. I had to pull out my computer and walk the agent through some of my published work while explaining my career. She then asked me why I was applying in Jakarta and not in my home country.
My recommendation is to keep the documents you apply with handy upon arrival in Thailand, perhaps in a folder always accessible on your mobile.
For context, I have spent time in Thailand d and do have a couple of visa exempt entires.
Hope this is helpful to those that I have seen asking if this is happening.