Corruption is literally the oil that keeps the system operating. It's built in, and it's centuries old here. Things like the the kin-muang system and tax farming were based on the people in charge of things being allowed to skim money/goods from their subjects as a perk of their position. Fast forward to today, and ordinary police are not well-paid and have to shell out of pocket for a lot of items that are provided in other countries. Being able to skim some baht here and there made up for that. And a cut is sent up the chain so that the big guys that dole out positions and keep the system running smoothly get their reward as well. Reform would mean a total revamp of the system, from top to bottom, not just some find-tuning. In other words, it's not a good system tainted by corruption, it's a system that depends on corruption in order to function.