Here's my $.02
Let's compare a business, such as the software business you mentioned, to a Real Estate Investor's business.
With a software business, the business owner has to do the following to generate a successful business organization. (Not necessarily in order) The Software Business (I'll use SB as an abbreviation from here on) has to design a product. That product has to A) fill a need B) The need has to be large enough that the target market can generate sufficient scale to generate profits and C) has to be either difficult to replicate by competitors or protected by intellectual property rights. The SB then has to spend human capital to develop the product, test the product, then distribute the product. Before the SB can do that, they have to decide how to price the product, how to source the manufacture of the product, hire employees to handle product enhancements/bug fixes, hire employees to distribute the product, hire attorneys to protect the IP. The SB has to determine additional product lines and markets to enter to prevent the inevitable obsolescence that comes with software, etc. You get the idea, you could go on and on for days talking about the things they have to do.
Contrast that to Real Estate Investors. RE is the product. Compared to another business, REI has much lower thresholds for product development and marketing. Whereas a SB has to do their own market research for their product, there is ample market data for real estate in any market. Not only that, but there is no need to hire a sales force to market your widget with REI because RE Agents already exist in every market. As for market data on the need for your product as a REI vs. SB that information is also readily available. Due to the nature of the sales, product development, etc of REI a RE investor can have a very small (often times zero) need for additional employees even with a large dollar volume of business. Capital is readily available for REI at known leverage ratios. SB or other businesses will be on a case by case basis so funding is unknown.
What a REI does is develop a process, what most businesses do is develop a process AND a product.
Now, let's look at the numbers because I think you'll find that the numbers you posted understate the returns of REI as well.
So, let's take a pretty generic case study. We'll use 7% cap rate on a $500,000 multi family property with 10 units. It would be completely reasonable for the buyer to assume (based on naahq.org's 2014 numbers) that expenses would run about 40% of revenue, and CapEx would run 8% of revenue. So a 7% Cap gives you $35,000 of NOI on a $500,000 property. Using naahq.org averages that means you have a gross rent of $58,333, $23,333 of normal operating expenses including vacancy $4,666 of CapEx reserve and a total net revenue of $30,333 at the end of the year. Assuming a 20 year amortization on a 5 year maturity mortgage of 5% interest and 80% LTV (so $400,000 initial balance) your yearly payment is $31,677. (It's obvious at this point the debt service is greater than your net, but again, capex is a reserve not an actual expense YoY, and this example is deliberately a very mediocre set of numbers to illustrate the point). So, let's just go with these numbers. Each year you come OUT OF POCKET $1,344 AND you put $100,000 into the project to begin with. We'll also need to make some assumptions about rent growth etc. Let's assume rent growth at the historical rate of inflation of approximately 3%. After 5 years here's how the numbers look:
Rental Income $65,654
Expenses (40% of RI): $25,496
NOI $40,157
Estimated value at 7% Cap Rate 573,678
Estimated Cash flow net of debt service $30,362
Approximate CapEx Reserve $24,000
Amortized Loan Balance 333,819
So final numbers are 100k invested, equity at 5 years $239,859 with a positive cash flow of $6000 during the 5 year span. If you just average the cash flow over the five years at $1200 (again just making this example simple, it's a bit more complex than this) you get an average annual return of 20%. NOT a bad return on a VERY average set of numbers, especially considering the limited barrier to entry to 'owning' a business.