Some of the people pulling night shifts are unable to integrate into society because of drug or alcohol problems, or because of stigma against people with mental illness, or because of learned helplessness.

There's not much difference between going through trash to get soda cans or being the guy who stacks the dishwashing machine, except that dishwasher guy loses the job if he doesn't turn up whereas the can-gathering guy just loses a night's wages.

EDIT: But I do strongly agree with your post. Criminalising this seems wrong headed - these people are helpful to society and are working, and we should be thinking of ways to help them.