It's not that easy. You need almost as much fuel to return from Mars as to get there. The payload to (fuel + overhead) ratio for a trip to Mars is horrendous. There is no booster or staging system that exists today that could take anyone from earth to Mars and back. Those Mars Rover gizmos do not have the overhead of keeping human beings alive and we have absolutely zero chance of bringing them back. The whole idea is a non-starter.
#39 re ability to leave Mars. Haven’t you seen the Movies “Mission to Mars” (I think it had Michael Madsen and Val Kilmer and Cary Ann Moss, and another like it with Don Cheadle who does leave Mars by other means?
Seriously, due to Mars lighter gravity, space ships could be assembled from parts shipments on the planet, fuel added, and Voila, you’re homeward bound, not that we would want any Martian Marxists coming back to wreck earth a second time.