They should pay more.
In this case, you'd note that there are certain businesses that don't consider themselves viable at the current value of unemployment benefits if unemployment behaves as it does right now. Then you see if you're okay with losing those businesses and if you are, then so be it, you think it's worth the trade-off. If you're not okay, then you need to tune the intervention, e.g. unemployment is guaranteed for some time even if you become re-employed, or 'unemployment' is guaranteed to all, or you lower the payment, etc.
So yes, you are right that there are many parameters that can be tuned.
Your own comment refutes this, you just use different wording. Policies are created with certain goals in mind, i.e., how things should be. You then see whether your policies have achieved this goal, and reevaluate accordingly.
I just mean that making some policy and then saying "businesses should do X" isn't useful. That's like making a phone a certain shape and then saying "people are holding the phone wrong".