Someone is really pulling your leg. Every Mercedes made to date has a drain plug in the bottom and an oil filler in the top, just like virtually every car that's been built since the Model T.
Yes, the dealer uses the vacuum system to draw the oil through the dipstick hole, but you or the Quick Lube can still pull the plug and drain the oil just like any other car. Good luck,
David C. Klasse,
Worn out engines hurt the environment too. Drained oil is recyclable. Oil and other tailpipe emissions that make it into the air are not.
Have a great day,