All cash businesses; taxis, ice cream vans, tanning salons, car washes and takeaways are ripe for organised crime to set up as fronts to launder drug money. Takings can’t be traced and the books will appear far healthier than actual customer footfall would ever suggest.
Aside from making bad guys richer and swindling the exchequer, they also harm genuine businesses as they aren’t trying to make a profit and can undercut competitors.
Exploitation of immigrant staff, no regard for H&S, minimum wage, snapping up cheap lets and moving on quickly if the authorities get a sniff all add up to making them a size-able and difficult to eradicate problem. Investigations take months, witnesses are intimidated, cases fail. Even if convicted and banned from operating, their wife, niece, dog, budgie takes over the next directorship.