Take a look at "Work involving continuity of operation" part. Amazon warehouses have 4x10h system AFAIK.

You can legally opt out of the working time limits in most professions, except for limited few like truck drivers. I'm yet to see an employment contract that doesn't have a clause for the opt out. I work as a programmer contracted for 37.5h/week but of course there's a clause in my contract to say I agree to work more "if needed"(never had to in my 7 years of work here, but still).

Overtime on UoP is permitted, but regulated. You can't do over some limit (like 400 hours yearly); except if you're a doctor.