> Many issues are simply as black and white.

That's how partisans think. You're using this as an exemplar of something which is black and white when it's exactly the sort of thing which is highly variable and context dependent:

> tax breaks for the rich don't trickle down

The general thing you want is for money to go to things that are productive and increase competition for the supply of goods and services. If it's spent on building housing then people get jobs building housing and housing becomes more affordable. If it's given to a company that builds tanks the army doesn't want who spends it on lobbying to get even more then ordinary people receive no material benefit while paying part of the cost, and suffer the opportunity cost of it not being used for a productive thing.

Which implies that tax breaks for anyone building productive things like housing can be good, even if the developers are rich, because they use the money to expand their construction operations and increase the amount of housing that gets built. Whereas tax breaks for high frequency traders are bad because high frequency trading is useless and increasing the incentive to spend resources doing it is as counterproductive as building unnecessary tanks. But in the latter cases you still may be better off to do something to thwart it rather than taxing it and giving the government a perverse incentive in the form of revenue to cause it to expand.

Moreover, the premise of supply side economics is that business owners have the incentive to spend the money increasing productive capacity so they can get more sales, when one of the other things they can do with it is to buy up the competition. That doesn't imply that the former never works, what it implies is that it only works in combination with meaningful antitrust enforcement to prevent the latter from happening instead.

Which is to say, it's not black and white.