Or how about cops don't take armed donors out on patrol?
		
		
	 
How about cops don't have 'donors' at all. 
Where I come from, giving money to the cops is called 'corruption'. That doesn't stop it from happening; but at least everyone has the decency to recognize that it is nothing to be proud of. When the 'donations' or their consequent favours become public knowledge, people go to jail for it. They don't get compared to benefactors of the Red Cross. 
Simple rule: Cops are funded from taxes. They should never ever get money, goods, services, discounts or gratuities of any kind, and their government funding should be high enough to minimise the temptation to take those things 'under the counter'. For the police to be effective they must not only be above corruption; they must be seen to be above corruption. 
Even such 'mostly harmless' perks as getting discounted food at McDonalds is unacceptable. Any person or organisation might at some time be investigated by the police; and if and when that happens, the police need to be able to honestly say that they are impartial. 
If a rich man donated half the police department's equipment, just how confident can we be that he will be shown no special favour if accused of a crime?
I know it goes against everything the USA stands for, but the law really should not consider a person's bank balance when investigating their possible involvement in crime.