You'll have a few options once they move out; you can increase the rent to cover the difference, have the studio metered separately or write a clause into your lease that they pay either a portion of electricity or that they pay 100% over a predetermined amount.

It's grabbing a few data points and building a pre-determined narrative with selective data.

If you are valuating SFR's focus on  other long-term plays like debt pay-down, equity, and tax benefits...Not discouraging your valuation..practice helps...but your vacancy loss is pre-determined as a component of GOI...it's not an operating expense...and capital expenditures are what they are...again, not an operating expense (and 15% may be excessive...).PM me or feed me a couple of your property addresses and financials and I'd be glad to help you sort these out. 

Can be 50/50, 60/40 or a predetermined amount such as $500 or more.The simple answer to your question about how does the investor make money. 

Today Many electric utilities have graded service rates to encourage efficiency and bill you at a higher per KW rate once you reach predetermined consumption thresholds.Likewise, some ISPs will bill you at a higher rate when you go over your package data threshold.If your ISP is blocking your traffic when you reach a threshold it's an indication they are infrastructure constrained - or "business constrained" - and you should be looking for a different provider.

I think a lot of people look at the topic from a fixed/predetermined mindset.