Far easier and more profitable, from a power, status and bureaucratic perpetuation standpoint, for each branch to nibble at separate regions of the unregulated sphere. If the government was truly limited initially, it can take quite some time until the branches come into unavoidable conflict. And when they do, they have options beyond simply checking and balancing each other. They can arrive at modi vivendi that beat zealously opposing the other branches at the margin.
I suspect the vote is supposed to supply a lot of the check and balance to the rest of the government, but it doesn't work terribly well.
Here's a notion for improving the situation: you get extra votes if you're punished by the government. One vote for each six months in prison (including time spent awaiting trial). One vote for each year on probation. You retain these extra votes for the rest of your life.
One vote for each percent of your income taken as fines. These votes get used up, but if it takes a while to build up to an even percent, so be it.
Extra votes get applied to the jurisdiction that imposed the punishment.
I'm not sure what the appropriate answer is if the government kills you. I'm thinking 20 votes plus 5 for each estimated year lost, to be given to friends and family. There are obviously some logistical problems.
There are more problems associated with restrictions on liberty that don't lead to formal punishment, but perhaps it's best to have a bright line.
A this point, you're probably wondering why I'm suggesting that criminals get rewarded. The reason is that the government gets rewarded for punishing people--fines are an obvious conflict of interest, and prisons represent money that the government can hand out.
Under this system, the government can punish moderate numbers of murderers and thieves, but there's some reverse pressure if too much is made illegal or the punishments get too severe.
I'm not sure how serious I am about this solution, though I'm quite serious about the problem. If you've got other solutions, please let me know.