Your solution is effectively corporate welfare. The free market should determine whether customers will order packages or not.

Also, you are suggesting that the government should provide an easier means for businesses to serve their customers in a way that gives them an advantage over the local businesses that pay local taxes on purchases.

The real solution is to make delivery companies pay for the congestion they cause. A fair use tax, for example. Then, using that tax revenue, you can improve traffic. The delivery companies can pass their costs on to the retailers and the retailers can pass the costs on to the customers. The customers can then decide whether they wish to pay more or shop somewhere else.