There’s a lesson here. Don’t be a pest when you’re only a guest. Telling folks they’re engaging in bribery (what they call “gratuities”) doesn’t work well. The fellow was a missionary not a cop.
Exactly. Most places you can refuse to pay such gratuities and you will still get the permits and other required paperwork, eventually. If you don't have several years to wait or don't want to have to repeatedly file amended paperwork as the powers that be find technicalities to delay you with, then you pay a gratuity to someone to oversee your paperwork and ensure that the small problems that arise are handled right away and that all the paperwork is in order. Your choice.
Besides, if I'm not mistaken, they do have police and others who are in charge of investigating such accusations of unsafe practices, he could have filed a complaint with them and if he was really concerned that someone might be injured or killed due to the illegal practices, he could have paid someone a gratuity to make sure his complaint was handled as quickly as possible and that all of his associated paperwork was in order.
Basically, the guy's a dolt. If he wasn't smart enough to fight fire with fire he shouldn't have been there in the first place. Thailand is far worse than I've heard India is and you can have someone out to investigate an unsafe working condition or unsafe building practice the day after you file a complaint if someone who knows their system takes a personal interest in making sure it moves quickly through the system. Naturally, you'd want to show your appreciation to someone who is so conscientious and who is every bit as interested as safety as you are.
JMHO
I believe their complaint was that the bribes served to official overlook UNSAFE BUILDING PRACTICES!!
Much different than simple greasing the skids!