The example of doctor doesn't really apply to my question. I don't think most doctors are the type of people who would stop working out of being lazy. Most doctors are passionate about what they do and are highly conscientious

I'm talking about the more menial, less interesting jobs that are still vital for the production of the basic necessities you seem to take will be there for granted under socialism. Someone has to drive the trucks that carry the produce from the farms. Someone has to work the odd jobs around the farm. Someone has to work the grill at the burger joint. Etc etc. We're not at the point where we could just automate all these things (if we were they already would be.) These are not exactly the most desirable jobs. So why wouldn't people just simply opt out of working them if they know the system will provide for them anyways? And how would a socialist society get people back to working those undesirable yet necessary jobs before everything collapses?