"Why the tab in column 1? Yacc was new, Lex was brand new. I hadn't tried either, so I figured this would be a good excuse to learn. After getting myself snarled up with my first stab at Lex, I just did something simple with the pattern newline-tab. It worked, it stayed. And then a few weeks later I had a user population of about a dozen, most of them friends, and I didn't want to screw up my embedded base. The rest, sadly, is history."
If you don't care about compatibility with existing Makefiles, you can do this already with GNU make; just set ".RECIPEPREFIX" to some other character.
At least every 2nd C programmer working on a non-unix platform has been burned by this at least once.
It's like a 10ft deep pothole on Broadway that won't get fixed because traditionalists see it as a 'national monument'.