Is mandating the government to allocate at least 20% of its budget for education a good idea? I don't know. But surely it has a downside: it creates a distorted incentive, especially when the budget for education has never been that high. People care more on how to spend the budget and less on making priorities and finding what really works.
This is an example of the distorted incentive at work: creating elementary schools with "international standard." Is it the priority for now? For me, some other problems need higher priorities. First, quantity and maintenance of school buildings, especially junior secondary schools in remote areas. For every 7 elementary schools, there is only one junior secondary school, so achieving a universal enrollment rate for children aged12-15 is more difficult. Don't get me start with the physical quality of existing schools.
Second, lower cost of schooling; not just tuition fees but also expenses for books and uniforms.
Third, teacher management. Pupil-to-teacher ratio in Indonesia is about 14 to 1, that's quite low. But the average class size is 37 students. This shows that we have oversupply of teacher with short working hours. Geographical distribution of teacher is also another issue. Sixty-five percent of all schools in Indonesia are overstaffed. Yet we often here the stories of a single teacher taking care of all students in a remote school.
Then you can add the quality of teacher, low perceived return on education, and other issues that are in higher list of priorities.
Of course, having more schools with international standard is good. But, for Rp1 billion allocated subsidy for three years to each school - with only limited number of students can be admitted - surely there are better ways to spend public budget. And, should such project be a public-sector one? The private sector can fill the gap for the international-level schools (and they have done it), while public budget will be better used to improve access.
Update: a friend of mine wrote this op-ed about another idea to use education budget to improve PC-per-student ratio. Again, the idea is good. But when you think you have tons of money in your pocket, you care less on how to spend it efficiently.