Why are Windows 10 crashes not getting reported to Microsoft?
I haven't been able to confirm this 100%, but based on recent observations I believe these crash reports are tied to the "Optional diagnostic data" option in the "Diagnostics & Feedback" settings.
A few days ago I changed this setting from "Required diagnostic data" to "Optional diagnostic data", and crashes that have occurred since then are now showing as "Report sent" in the Problem Reports Viewer.