She only paid $180 of her balance and nothing else that week. 

Even with a generous grace period, although the tenant is current on rent, there are late fees from 3 months' rent on her balance. 

SureShould we ban the practice of medicine because of that?

Then give some real time for dealers, and doctors that prescribe thousands of pills a month to one patient (knowing they couldn't possibly need them for a legitimate purpose) and take the license away from the doctor to practice medicine.

As a physician I am much worse off since the advent of Obamacare and the future of medicine care and practice is dim.

Car dealers promote their car sales, make up manufacturers promote them miracle products, Pharmaceutical companies promote their medicines, everyone promotes something.

They'll have exhausted all other options of over the counter medicine or whatever. 

The reason to do this is to get a base line so you'll have something to compare against when creating a deal with the seller.One path to explore is to see what her sales price is (if it's fair and agreeable) then subtract that amount from her balance on her mortgage and that would be her gross equity.

I have a career in medicine as a physician assistant and own 1 rental property (single family home) my wife and I have owned for about 6 years.

If you don't know her balance and she won't tell you, then there's no way to make a deal.