Premiums for a silver plan can easily be $30k per year for a family of 4. If an employer decides to cover 70% of it instead of 80%, that is literally a pay decrease of $3k, not to mention possible changes in coverage, deductible, and oop max.
For example, the employer could keep the 80% subsidy, but increase deductible from $1k to $10k. Unless premiums go down a lot that is basically a huge pay decrease too.
And you can be pretty sure that many workers would walk if the extra goodies they are accustomed to but which ain't guaranteed were to be withdrawn. Assuming the competition still provides them.
I don't know how available this is to folks who aren't Mennonite or Mennonite-adjacent, but it's there.
The mainstream Anglo-American attitude around this kind of support leaves me scratching my head a lot of the time.
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0: Tithing can take many forms beyond giving cash. I tithed my RSUs.