How do freelancers get away with freelancing as their primary income without PR or spouse visa?

I've been seeing a lot of foreign freelancers in Japan lately (photographers, videographers, content creators, etc.) who seem to have made their freelance work their main gig, yet they clearly don't have a PR or spouse visa based on what they've shared.

From what I understand about Japanese visa restrictions, a normal work visa (like Engineer/Specialist in Humanities) ties you to specific activities and technically doesn't allow you to do unrelated work or have your side hustle become bigger than your main job. I know there's some permission you can get, but I thought that was very limited?

Yet I see lots of people thriving as full-time freelancers (such as content creators, but not only) and not mentioning any traditional main job.

Concrete example: freelance photographer who also works full-time for a magazine but CLEARLY labels themselves as freelance and has a bunch of side-gigs they promote on their website.

How does this actually work visa-wise?