If they are not real jobs maybe they shouldn’t pay taxes on their income.
They often don’t.
At the same time, you often can’t put down informal employment on a job application.
When I was in college, I applied for a number of jobs - I had done a few things like tutoring younger students, stuffing envelopes, etc.
Professors and University staff told me that they couldn’t accept those things as experience. There was no proof I had actually done them. These were the days before e-mail was widely available, they told me they couldn’t make toll calls or otherwise check to see if my references actually existed.