Zero-based budgeting (ZBB) emerged in the 1970s as a response to the perceived inefficiencies of traditional incremental budgeting. Incremental budgeting typically involves taking the previous year's budget as a baseline and making marginal adjustments, often leading to the perpetuation of outdated programs and inefficient spending without rigorous justification.

The Intent of ZBB: ZBB's core principle is that every expenditure, regardless of whether it's a new or existing program, must be justified from scratch for each new budget period. It requires managers to:

1. Identify Decision Units: Break down the organization into manageable units responsible for specific activities.
2. Develop Decision Packages: For each unit, managers must identify alternative ways of performing activities, analyze costs and benefits, and propose different levels of service or funding (e.g., minimum level, current level, enhanced level).
3. Rank Decision Packages: All decision packages are then ranked in order of priority, allowing resources to be allocated to the most critical and cost-effective activities.

The primary goal was to foster efficiency, eliminate wasteful spending, reallocate resources to higher-priority areas, and challenge the status quo by forcing a comprehensive review of all activities, thereby breaking the cycle of incrementalism.

Why ZBB Often Becomes Incremental: Despite its noble intentions, ZBB has frequently been criticized for failing to achieve its anti-incremental goals and, paradoxically, often becoming highly incremental in practice. Several factors contribute to this:

1. Overwhelming Workload and Complexity: ZBB is incredibly time-consuming and data-intensive. Requiring every department to justify every line item from zero generates an enormous volume of paperwork and analysis. Managers often lack the time, resources, or analytical skills to perform this task thoroughly, leading to superficial justifications.
2. Information Asymmetry and Gaming: Department managers possess superior knowledge about their operations compared to central budget authorities. They can strategically frame decision packages to protect their existing programs, making it difficult for central authorities to genuinely challenge their justifications. They learn to 'game the system' by presenting a 'minimum' package that is essentially the previous year's budget, making any cuts seem catastrophic.
3. Political Realities and Resistance: Budgeting is inherently a political process. Existing programs often have powerful constituencies, vested interests, and political champions. Cutting or significantly altering these programs faces strong resistance from departments, employees, and external stakeholders. Political executives are often reluctant to make drastic cuts that could lead to public outcry or job losses.
4. Lack of Clear Objectives and Performance Metrics: Without clear, measurable objectives and performance indicators for every activity, it becomes challenging to objectively rank decision packages. In the absence of such metrics, decisions often revert to historical allocations or political expediency.
5. Focus on Cost-Cutting over Strategic Planning: While ZBB aims for strategic resource allocation, its implementation often devolves into a cost-cutting exercise. This can lead to short-sighted decisions that undermine long-term strategic goals or essential services, making managers wary of proposing genuine alternatives.
6. Bureaucratic Inertia: Organizations, especially large government bureaucracies, are resistant to radical change. The effort required to implement ZBB effectively often clashes with established routines, power structures, and the comfort of incremental adjustments.

In essence, the practical difficulties, political pressures, and human behavioral aspects often lead ZBB to be implemented in a way that mimics incremental budgeting. Managers, overwhelmed by the task, often start with their current budget and then justify it as if it were a 'zero-base,' or they present a 'minimum' package that is barely below the current level, making any further cuts seem unfeasible. Thus, what was designed to be a revolutionary departure from incrementalism often ends up reinforcing it, albeit with a more elaborate justification process.