When reinstalling MacOS onto a "Macintosh HD -Data" partition created by BootCamp, it fails every time

The "Macintosh HD - Data" volume is one of several new APFS volumes utilized by macOS 10.15+ and is completely normal since that is where your home user folder is located where your personal files are stored when using macOS. This has nothing to do with BootCamp or Windows. Plus the "Macintosh HD - Data" is not a partition, but actually an APFS volume within a hidden Container holding other macOS APFS volumes. The hidden Container is more like a partition even though the APFS volumes have a similar appearance to partitions.

About the read-only system volume in macOS Catalina - Apple Support

Signed system volume security in iOS, iPadOS, and macOS - Apple Support

The macOS system files are stored in the "Macintosh HD" volume. When reinstalling macOS you must either select the "Macintosh HD" volume (no "Data" in the name) or perhaps to the hidden Container (I'm not exactly sure since I've never reinstalled macOS without erasing the entire drive or Container. You can see this Apple article for details on how to reinstall macOS:

How to reinstall macOS - Apple Support

The fallacy of this might be related to choosing "Erase" in disk utility versus "Erase Volume Group".

Erase just does this:

Apple SSD - Hardware

(APFS CONTAINER) - has been touched by boot camp before

> Macintosh HD (Read Only)

> Macintosh HD - Data ( Erases only this APFS Volume )

Erase Volume Group does 'this':

Apple SSD - Hardware

(APFS CONTAINER) - Erases this

> Macintosh HD (Read Only) (Rebuilt from ground up upon attempting to Reinstall 10.15+ macOS)

> Macintosh HD - Data (Rebuilt from ground up upon attempting to Reinstall 10.15+ macOS)

I think the weakness is the former example, the APFS container has an unknown issue that BootCamp touched upon.

However, if you still value boot camp, its possible the Boot Camp windows partition is lost in the process. Best to back that stuff up, and just re-configure Boot Camp over again if that's the end goal.