The Every Student Succeeds Act’s brand depends largely on the flexibility it provides states and districts. Yet one of ways it was designed to provide schools more freedom, in this case for funding systems, has been almost totally ignored. Now the Congressional Research Service has identified possible reasons for that. One potential culprit? Father Time.

First, here’s what we’re talking about: Included in ESSA is a “Flexibility for Equitable Per-Pupil Spending” authority. That’s the fancy title for a pilot program allowing up to 50 districts to consolidate their federal, state, and local funding to create new, weighted per-pupil funding systems. ESSA requires these new systems created through the pilot to provide significantly more aid for students with significant needs.

Districts such as Denver and Indianapolis have moved towards similar funding systems. The pilot, which districts must apply for, didn’t exist before ESSA. It’s part of Title I, the section of the law geared towards disadvantaged students. It grabbed a decent amount of the spotlight in edu-land after President Barack Obama signed ESSA in 2015.

But it’s been a distinctly unpopular offering. In fact, just six districts have applied to take part, and only one, Puerto Rico, got the green light from the U.S. Department of Education. However, that green light for the U.S. territory turned red earlier this year: The department rescinded Puerto Rico’s participation in the pilot program because the island went ahead with its plan without first getting federal approval for proposed amendments.

You read that right: That means not a single district is participating in the pilot. And the one district that got approval to do so lost it.

The CRS studied the lay of the land for potential reasons why the pilot’s mostly been treated like last week’s banana. Here are some of the possibilities identified in the service’s report, which was released last week and written by Rebecca R. Skinner:

• The pilot only lasts for three years. Districts might have made the calculation that it’s not worth the (potentially quite considerable) effort and time to switch over to a weighted student-funding system, only for the pilot not to get extended.
  
• Speaking of time: The CRS notes that although ESSA passed late in 2015, it took the Education Department until February 2018 to formally get the pilot off the ground. By then, some districts might have lost interest or put the matter aside.
  
• Districts wouldn’t be allowed to consolidate federal money for students with disabilities or career-technical education through the pilot. On a related point: districts that operate school-wide Title I programs can already combine certain federal funding, including pots of cash earmarked for special education and CTE, with state and local money.
  
• There’s also a less technical, more political factor possibly at work. To quote the CRS report: “It is possible that some LEAs may view the consolidation of federal funds and the resulting redistribution of funds among public schools in the LEA as a step toward the portability of federal funds, whereby funds would be associated with individual students rather than schools and could ultimately follow them to any school of their choosing, including a private school.”

Keep in mind the CRS doesn’t lay out these explanations as definitive; the report says it’s ultimately “unclear” why the pilot hasn’t been popular.

Separately, we reached out to Jeff Simering, the legislative director for the Council of the Great City Schools—which represents 75 of the largest urban school systems—for his thoughts on the pilot. He said that since 2015, he could recall only one district asking him about the pilot, and that this district ultimately chose not to apply.

One major concern Simering highlighted is that participating in the funding pilot could ultimately lead to consolidated funding going to schools with virtually no disadvantaged students. There would also be additional and likely unpopular requirements for districts using the pilot when it comes to calculating salaries at different schools. And Simering added that it’s easier to overestimate just how much freedom districts would have under the pilot.

“Often when Congress offers flexibility options, the process of reaching such a bipartisan agreement typically carries with it a series of additional requirements, which ironically tend to constrain the extent of that flexibility,” Simering wrote in an email.

Read the full CRS report below: