Facepalm

I'm pretty sure the opposite is true, someone has implemented a date entry to be always different than the default in user's region

Microsoft is even worse, they do some places on region default, some places mm-dd-yyyy and some rare places in yyyy-mm-dd. I remember the worst example being powershell module for exchange server and message trace log. It'd output your region's default, but accept as input only mm-dd-yyyy