PR is not a state in the union, and neither is Washington, DC. There is one big difference, DC pays federal income taxes, in fact pays a higher percentage than at least 22 states. Also, DC has over 700,000 population, more than Vermont and Wyoming. Why should the 700,000 DC residents NOT have the right to be represented in Congress and help determine how their tax money is spent. Is that fair?
You mean aside from that Constitution thingy?
The reason DC is not a state is obvious. The founders realized the capitol city would always have a conflict of interest. The people in DC would always vote for more and more largess. Life isn’t always fair. Get over it.