Ultimate control is transactional control. The highest expression of that would be a CBDC.

You owe a fine or taxes? We'll just take it from your balance. We want to limit your travel? Your money only works inside your city. We want to control your rate of spending? Interest rates are so last century, we'll just put a expiration date on your money. If we want to ban certain things we will just turn off transactions. We can limit or eliminate guns, pornography, alcohol, meat according to the date, area of the country, or by citizen.