Our Roadster doors close under their own weight - in fact we avoid anything resembling a "slam".
But it is a Morgan so maybe there are lots of variables?
After 31 years, my door hinges are a bit slack, so with the weight of a sidescreen they do need a bit of a slam. I've fitted the Librands sidescreen steadies, so the inner knob makes a very good handle.
If I have a passenger, I wait until he/she is seated and close the door before I enter the driver's seat.
That, sir, is because you are a true Gentleman!