"in proportion to the settled AHV payroll of their employees"
I'm not sure how you equate AHV with rent, as it seems to be a social security / retirement system, and furthermore I'm under the impression that it's only used for the payroll data, with the money going to employers.
As for making huge amounts of money while holding money (around 87CHF * 8M for <1 year?) - is it really that huge and aren't they already holding orders of magnitude more money?
>via health insurance companies, though that shouldn't make a difference.
The difference is huge, in the time between income and give it to the citizens you can make huge amounts of money with it.