I suppose that's true, but if a minimum wage employer doesn't offer health benefits, for example, then taxpayers pick up those costs. We know this happens, because we can see who is on Medicaid, and MANY of them have jobs with various low wage employers. Walmart is by far the biggest employer of those on Medicaid, but in my state the biggest as a group are apparently now 'staffing' companies that fill all kinds of low wage positions - warehousing, cleaning, etc.
So we could as society remove the safety nets and these people and their kids, when they got sick, would just get denied care and many would die. In short order, there would likely be protests, walkouts, etc. and employers in a 'free market' perhaps unable to fill those positions without some base level of benefits. Or they'd fund company clinics or find some other way to keep their workers from revolting. But it seems clear that those healthcare costs would be shifted back to employers somehow, at least in part. Mothers aren't going to work a job that if they do what's asked, still won't allow them to afford healthcare for a sick child or themselves if they get sick, not in the U.S.
That's how I look at Medicaid as a subsidy - it allows for low wage labor while keeping the peace in workplaces in many industries, and taxpayers pick up that cost. Not sure how else to accurately describe what the net effect of safety nets are to employers of low wage labor. We make that low wage job possible, in part at least, by assuring some basic level of subsistence no matter how low the wage or whether or not benefits come with that job.