It's trivial to capture if there is a will. Send an agent who offers a bribe, fire the worker if the bribe is accepted.

One trick it to leave a desk drawer half empty and then they go for a tea break. If they come back and they don't see money in their desk drawer, then it's hard for you to complain when they mark something in your forms as incomplete and ask you to redo it or whatever. And the next time you come to the office, you might be accidentally left to wait for a couple of hours and how you do make a decent complaint about that?

Same for me registering a car. The dealer sent me 12 documents and the inspector wanted a few more. The dealer wasn't clear what they were. So I had to waste a few hours for two days. The agent was able to cut the queue and I spent as much time as to expose the engine number under the bonnet. The agent is the funnel for bribe from me to the department.