Who are mostly Black....And doubtfully pay taxes in the first place.
Not necessarily. I don’t know about Ferguson, but local taxes tend to be property or (rarer) sales-based.
Even renters pay property taxes, just through their landlords. Yes, they may pay that rent from welfare, but my recollection is that welfare isn’t necessarily indexed to rent. At least not alone (COLAs include other factors) So raising taxes will still reduce the level of dicretionary (in this case welfare) income in the citizens’ pockets.