You ask them. If they say no, then they can't pay rent.
"OMG everyone is going to totally take advantage of this!"
Not everyone, but yes, plenty of people and business will.
"OMG that's unfair."
Yes, I acknowledged that from the start. The whole point of my argument is that this might still be preferable to the alternative, it might still be better than sticking to what's 100% fair, because collectively we might emerge stronger from this crisis if struggling businesses are afforded leniency, while the rest of us keep paying our bills on time.
But thank you for perfectly illustrating my sidenote on how this way of thinking is completely alien to many Americans.