well yes? Can you imagine working on a hot building site for 8+ with no sun shelter provided or even allowed onsite? a simple gazebo is a godsend, and very cheap for employers to provide, its no surprise something like that would be regulated.
Heat exhaustion and skin cancer are common in those kinds of industries.
If you can find a way for e.g., roofers to work in the shade, in sure you'd be handsomely compensated. Most of the building trades work in the sun by default.
It was just me trying to be a wiseass by reaction to OP argument that I felt like "omg next they'll want to regulate the sun!!11" by answered "yes actually yes, there is a regulation about the sun".
Heat exhaustion and skin cancer are common in those kinds of industries.