Where did I assume that?
Here.
Without determining elasticity, it's impossible to determine how much of that cost is flowing through or how much goes to impact margin.
So what?
The percentage of rent that is taxes is exactly the amount paid in taxes by the landlord. Period. It is an absolute number.
Why do they need to have an effect on rent for you to understand that you're paying them?
Bobby gave Lisa $10. Lisa then gave $3 to Uncle Sam. What percentage of Bobby's money went to Uncle Sam? 30%. It's that simple.
No I'm not. This is pretty entry level econ material. Price elasticity is very well studied and there's plenty of resources to learn more about it.
Without detailed analysis there's no way to know if this is true, or how true it is. It is entirely possible for an increase in taxes to lead to no increase in end prices or even a drop in rent prices. It's a complex system.