Answer:
With the vast Atlantic ocean separating Britain from the Colonies such that a trip from one side to the other could take between 6 weeks to 2 months, Britain could not impose the control it wanted on the colonies and the colonies could not always rely on the British Government to make decisions for them because responses could take too long to be transmitted as they did not have the modern forms of communication that we do today.
Americans therefore not having the weight of the British Government on them had to come up with a Government that would manage their affairs and respond speedily to their own issues as well. The British for the most part let the colonists do what they wanted so long as they purchased British goods and maintained loyalty to the crown.
After the president gets a bill they can choose to either approve or veto it. If they veto it goes back to congress to be voted on again. If he approves it becomes a law.
