Data is submitted voluntarily - I'm curious how thorough the submitted data is and which jurisdictions opt not to report.
I imagine it's not in the interest of public officials to submit data which weakens their authority, undermines or invalidates their positions - and that opposite holds true too.
The data seems less than substantial because it's not thorough nor potentially accurate, even when collected. Perhaps there's substance in comparing data here to data elsewhere to highlight official intent.
It's neat they have a public-facing API.