I personally witnessed a mid-aged female selling fruit, bagels, etc in a well-kept cart on multiple occasions not too long ago. The capitalist/libertarian in me appreciated what she was doing. My only issue concerned the health factors given she was selling in the subway where the rodents rule. Otherwise, everything in her cart looked super fresh and well prepared.
This person enters the USA illegally, steals produce for resale, doesn't pay for a street vendor's license, and avoids health department inspections and other regulations that legitimate street vendors and bodega owners must comply with; and as a result, she is taking money from legitimate business owners because they can't compete with illegal, unregulated businesses. And you are fine with that?
A lot of illegals also sell fruit cups as you mention. You see them a lot in Battery Park, the Financial District, the Seaport, and to a lesser extent Bryant Park. They are unlicensed of course and nobody bothers them. But other vendors need to be licensed, store their carts in City approved storage facilities etc. Haven’t seen the bagels for sale, but churros are also big. It’s all a scam. They are not being industrious per se. They are being funded and provided with the inventory, most probably by churches, relief organizations and maybe even the City itself.