Much of this money allocated to local areas is for “special projects” that must have central government approval.
Because local elected councils are restricted in this way, there is pressure on mayors and tambon councils from local citizens when they are unable to deliver on popular projects, and proper accountability cannot be achieved.
This means that one excuse for corruption can be that the allocation of spending is not controlled by the municipality or local tambon, and so the central government may be blamed.
This does nothing for encouraging democratic decentralis action.