LSCOLORS and CLICOLOR active by default and unset
The manual page for ls(1) documents the defaults:


  The default is "exfxcxdxbxegedabagacad", i.e. blue foreground and default background for regular directories, black foreground and red background for setuid executables, etc.


Those defaults are compiled into the ls binary - you can confirm this by browsing the source code. Note this definition in print.c:

static const char *defcolors = "exfxcxdxbxegedabagacad";