I've been asking: When the things that happen in a healthy free market aren't happening, what does that mean? (Maybe too abstract because I haven't got an answer from those I ask.)
More generally, I think the specific question is: if a worker is choosing between two companies, one which offers water breaks and one which doesn't, wouldn't they choose the first? This makes sense in a case of labor demand >> labor supply.
An alternative question is: if companies face a cost for worker injury, why wouldn't they take better care of workers. But there's huge amounts of evidence (including my wife's as a resident at Ben Taub) that injured workers are discarded into the public health system (with no insurance). And by "discarded" I also mean "lose their job" as well.
Finally, the cities largely bear these costs with only local property and sales taxes to support them, but have found ways to get around barriers erected by undemocratic rural and suburban legislators, and no doubt will continue to.
(A) there is no singular market. Each city, job, bidding process, and work crew is subject to their own specific market forces and expecting all to behave in an idealized way is silly.
(B) Your assumptions about what happens in a healthy free market are incorrect.