So this make sense but under the traditional home purchase scenario I need 20% down for the new house which would make selling our current home a necessity. 

They are also the items a property manager will gladly disperse a Professional to fix for top dollar on your dime.HVAC in Phoenix is a necessity in summer regular maintenance is important and changing or checking the filters. 

The way I see it is someone just starting with rentals who doesn't have a lot of money could buy them and rent to a renter by necessity.

The first home would be a necessity for I currently have no where to go after selling my home.

I do know most other homes on my block come with a garage so the nice sized shed i want to build is more of a necessity than anything.

I kind of stumbled into this whole rental investing thing by necessity, but I think I can see a bright future.

Finding a good contractor is hard and unfortunately a necessity in this business to get the work done.

Lastly, in your opinions, does having a property with a driveway to park a car a necessity or luxury in these areas (close to the city with public transportation)?

I think its somewhat a personal choice and surly when your young in your prime earning years are your desire is to leverage and grow.. then debt is a necessity.. for me personally I take on no long term liabilities  I usually have quite a bit of short term debt IE construction loans.. which as long as the market behaves create more cash flow for me in 9 months then the same dollars in drip income would over a ten year hold... but you know risk reward.. its always there.for me personally my long term contingent liabilities are less than 5% of my net worth and will soon be Zero.

On larger purchases like commercial apts or industrial,  I'll finance out of necessity but use private lenders.