I can't really speak on how healthcare works in the US, since I've never experienced it, but by in general I have a grasp of health insurance on a global scale.
In the UAE healthcare is mandatory, particularly in the capital city of Abu Dhabi. By law of the health Authority, every employer (with very few exceptions) is obligated to provide medical insurance for their employees, the employee's spouse, and up to three children. That's the law. However, given my current occupation in an insurance company, I know what sort of challenges people are facing and I see all sorts of cases where the employers are dodging providing coverage by having their their employees listed as "single" instead of "married" (when they are in fact married) thereby relieving themselves from any legal obligation to insure his/her family. The employee is in a tough position because while he could report them to the Health Authority, he risks losing his job and hence getting evicted since you need a job in order to stay in the country. It's a fierce catch 22.
Based on the stories I've been hearing about what's going on in the US, it sounds like quite a few businesses are finding loopholes to avoid covering their employees. For example, dropping employees' shift hours from 40 hours per week to 39 hours per week in order to technically list them as part-time instead of full-time employees and legally avoiding any obligation to cover them.