Eza isn't a reimplementation... it's its own program. The name of the binary is also eza not ls. What OS are you using that uses eza instead of ls? I have both installed and have ls aliased to eza because I find the coloured output to be easier to read (much like syntax-highlighted code is easier to read), but I've never seen eza pre-installed on a system, not does it conflict with ls. Package managers let you install both. They're different programs.