For those using photography as a second income to a main job, do you run your photography business as that, a proper registered business? Do keep correct accounts records for tax returns and declaration at the end of the year, etc? Or is it simply a "nod and a wink, cash in hand" for sales and work you do if you know that your income falls below your local country's tax thresholds?
More curiosity than anything about how people operate.
I recently stopped doing commercial work, but I ran it as a proper business for many years. Registered, with taxes and insurance paid. I would rather be above-board and legal. My income was above average. Too many people around here work for free or peanuts. If you're professional, people expect to pay professional prices and they don't think it's unreasonable. Never had any complaints about prices.
Wouldn't know how it goes in USA, but here we can register as self-employed business. Out of that you can have a full type or an "afternoon only". Those who run the afternoon only self employed business have a minimal tax, but in order to keep it minimal you must not earn more than a certain ammount of money per year or else you go to a higher tax level. And you can still have a full time job + afternoon business.
I know many photographers that are registered as that and it kinda pays off (I think the total monthly cost is around 30€ for accounting and paperwork service). You should check if there's anything like that at your place.
More curiosity than anything about how people operate.