In every other country, marines are subordinate to the navy and are used mostly in operations which fall under the remit of the term - seaborne attacks and small scale land operations which needed a quick reaction force. The USMC however, whilst being subordinate to the navy, occasionally performs duties which should be done by the army - occupation, large scale land invasions, air support, etc. They even have their own tanks and aircraft and receive more funding than the armed forces budgets of most states in the world.
Why is this? Wouldn't it be easier for organization and command purposes to absorb most of the land and air assets of the Marines into the Army?