US employers also seem to have a strong preference for young single employees - my theory is that this is because older employees with families are much more expensive to employ due to insurance.
Under the ACA, small businesses all end up lumped together in the same state-wide risk pool, so if my small business hires old or sick people it's very unlikely to affect our premiums. In most places this risk pool is larger and somewhat less morbid than the individual market.
I’ve been involved in hiring decisions where HR brought up the healthcare costs to complain, then stated clearly we can’t use that as a criteria for hiring.
I have doubts that human brains can separate out that kind of statement from our actions.