Most feel comfortable going the PM route simply because of the fact that everything is taken care of and you're guaranteed to have a person within the locale to take care of situations that may occur; otherwise, there are some tools available to you where you can bring a certain level of automation to that rental management process (ie. automatically syndicating a single listing to 10+ major listing sites, thorough tenant screening with full background checks, digital lease creation, automated online rent collection, and maintenance tracking).

My name is Charles Alexander and I'm a mechanical engineer currently living in Seattle, WA where I design automated aerospace manufacturing equipment.

This is a great example of why Zestimate's are not worth much, it's all automated and Zillow can only know so much about a property. 

It could be worth considering a shot at a software solution built for DIY landlords (1 - 15 units) to bring some automation to the rental management process, in turn, making things much much easier!

Any tips for automating this process? 

My rent collection isn't automated, unfortunately, so collecting late fee requires a slight increment of effort. 

That's why there are a ton of resources out there which can help you to turn away from PMs and towards being able to manage the rental properties yourself, with a certain level of automation brought to the process (ie. listing the property and publishing it to 10+ other major listing sites, comprehensive tenant screening applications which includes a nationwide criminal background check, credit check, eviction history check, and requires references for prior tenancy;  digital leases, payments/online rent collection, and automated maintenance tracking).

Ive heard that freddie mac has an automated underwriting system in which that process the loan and not someone else.

I just recently got back from a three year tour in Germany and the main thing you need from a property manager is someone with a solid automated system and  they need to be completely ok with email being the primary and possibly only form of communication. 

I will also be experimenting with permaculture/urban meadows and various ways to completely automate the AirBnB system, and passively cultivating fruits/vegetables on autopilot mode so as the mortgage decreases the amount of free food produced increases.