I'm not sure how you change this. I find it really grating how much contradictory cooking advice there is and how complex some recipes are without justifying the extra steps make any difference.
If you're making bread for example, some recipes will say don't add the salt with the yeast because it will make it rise slower and some recipes say it won't make a difference - it should be simple to confirm this with an experiment in a day to settle it for good and move on but for whatever reason this doesn't happen.
Is there a good reason why you couldn't settle how to caramelise onions with a few experiments?