I have had no issues finding renters for our units and have have minimal turnover.

The issue is cost.

He makes sure we maximize all deductions and have no issues.

It provides an opportunity to see what's happening in the units.You still have the ability to evict for lease violations, but your less likely to face non-payment issues. 

I've asked my clients a similar question and have developed tools for them to minimize this, but I find there are a few different types of clients.Manager managed - these folks have no issues as they simply upload their year end statement from their property manager, their 1098 mortgage statement and any other one-off expenses they may have paid for outside of the management company. 

We manage a property that was having drain field issues for awhile, got estimates and had the owner approve one of the vendors.

This may be because (1) until recently interest rates were trending lower so if the lender is getting a higher rate on subject note than he can obtain on new note there’s no monetary incentive to call the note (2) in the past technology did not exist to identify the property transfers (ten years ago county recording docs were not online) and (3) the lenders rather collect payments than own property.  

Why is this an issue?

Leverage will not change the effort or risk in the areas OP identified.  

While they may or may not be professionally managed, Class C properties will have some deferred maintenance issues and need renovations and upgrades.