Windows does care about file extensions but is mildly embarrassed about it, hence the "show" default that has existed from Win 8 (?) onwards.

Linux and co generally work with magic bytes which is just another way of doing file formats. Is it better to signify your file format with a .ext or otherwise?

I find myself turning on file extensions if I have to use Windows and on Linux, I don't care and it just works.

I think the UIs for Linux are better. I think that MS are hung up on trying to suggest their stuff so it gets in the way a bit. On Linux, you just get the best option based on what is installed.