Sadly, as a general rule, the cafe/restaurant owners don't really care so long as their old oil goes and the police are normally so slow to respond anyway that the thieves are long gone.
Because they travel to a different part of the country daily and probably won't re-do the same area for weeks or even months, they are almost impossible to catch in the act.
The ones I've experienced have an IBC in the van and tip the stolen oil into it and then dump the empty containers at the next place they steal oil from or in a back street somewhere.