I suspect that developers are not so much upset at salespeople getting commission, but rather why they get paid so much compared to developers. Personally I don't buy that sales skills are so much more difficult to find or are in higher demand than software development skills. Some of the difference in equity certainly has to do with the higher risk of getting fired for poor performance in sales. But beyond that it's…
Which in long term oftentimes costs more money then the non-existing feature was sold for. And it leads to bad relationship with customers - and somehow it is engineers who deal with those problems s not sales.