If she made any money she had to file taxes. If she made no money, it wasn’t really a business.
She says she filed taxes...but this goes back to the early 1990s, so you don’t have to maintain records to today (she has a point on that). Most folks I know who were doing this kind of work at the time....had contracts and made a fair amount of money, with tax issues that followed later because they did a lousy job of noting expenses. That may explain why she doesn’t have records now or want to admit that she fell into some tax issues later in life.
I used to know self employed guys in the construction business who worked by referral only, with no licenses or legal setup of any kind.
Most got paid by check, which they cashed in person at their cutomers' banks. They were careful to only deposit small amounts of cash in their personal bank accounts to stay below the IRS radar.