As long as they washed their hands after using the toilet - and didn't put their hands in their eyes ears mouth nose, after entering the toilet - then they should be sound.
Lives on surfaces for 72 hours, he could have coughed on handrails, door handles whatever. Touching and rubbing your face is something we all do unconciously, you could have picked it up from the cubicle door on the way in and rubbed your hands over your face before washing them. Even after going the loo and thoroughly washing your hands you could pop into WH Smith, M&S or Waitrose to grab something to eat - no other places were open, Greggs, BK, Costa all closed, so we all had 2 at most places to go for food and touch something he has touched, picking it up then. Even if you had handwash in your cab, you still have to touch the keys, door handle, handrails getting into the cab. The cabs are not cleaned between drivers, so the virus can be getting passed all over the place from one initial source.
The amount of contact a driver, especially store delivery drivers go through each day, when you think about it, can spread something so easily. One Saturday I did 6 stores across Liverpool alone, two weeks ago I was in Edinburgh on the Saturday, Reading and Rugby on the Sunday. That is why, when I thought I may have had Covid, I didn't work for over 2 weeks.