They are a little more management intensive, but the cashflow is worth it.On the other hand I have our former personal residence that we turned into a rental when we moved.

The OI district is designed for use on sites that have convenient access to arterials, since development of moderate to high intensity is allowed.The OI District is used to implement the Comprehensive Plan within those areas shown as part of the Rural, Suburban, Urban, or Compact Neighborhood Tiers.It looks to me to potentially allow/support residential development. 

I currently do cold calling but that again is very time consuming and labor intensive although roi is pretty good.

You can do it yourself through developing a team (more control but more time intensive); you can seek out good turnkey providers (less control but less time intensive); or work w/experts as a passive investor through syndication (little to no control and least time intensive).

Self management is not as labor intensive as people think with good systems, which is why #1 is important. 

I am curious, perhaps I am missing something, but it seems to me that property management is more labor-intensive than it is capital-heavy.

States require RE Brokers license, some have specific PM licenses, that may be less intensive as the RE one and even some states with no requirements at all.You should absolutely try and work for a established property management company, so you can learn and make mistakes on their dollar, and even get paid to build your knowledge base.You are 19, and have years ahead of you, So taking some time now to "pay your dues" will help you to avoid those same mistakes later, when they will directly impact your investments bottom line. 

I just haven't found one that wouldn't be labor intense from me.  

More upfront work and management intensive but it's all a matter of what you are willing to sacrifice to get to where you want to be. 

The due diligence process on the purchase was intense.