This is certainly true when it comes to the defense of your country, as well as the defense of a legal case. You cannot expect to get proper representation unless the person who holds the purse strings is the person being defended.
If it's not the person who eats the dog food who pays for the dog food, the dog food may not end up being fit for a dog to eat. That's even though the person paying for the dog food has very good intentions. It's not the amount of money that is spent that matters, nor the intentions of the one spending it. The Wedel chocolates will be ruined, if the free market does not serve as quality control.
I've seen people arguing that if the accused is entitled to a free defense -- to have an attorney appointed for him -- then a sick person should be entitled to free health care, too. If the one is a "right", why shouldn't the other be a "right"? Well, neither is really a right, because the doctor and the lawyer still need to agree to serve. Yes, I know, the government can pay them. But nothing that we don't personally pay for is going to be the same in value as what that amount of money could purchase if wielded by the ultimate consumer. That is the aspect of laissez faire that socialists don't grasp.
Ask anyone accused of a crime how helpful his PD is. Ask veterans dependent on the VA how great the service they receive is. Ask any dog whether he would rather eat dog food or your leftovers. You get what you pay for. What you personally pay for.