In all fairness not all businesses are on equal footing when it comes to the "cost" of hiring or expanding.
In Mike's case it seems that expansion and hiring would necessitate a new vehicle for that new hire to drive, therefore there are capital investment issues to consider which is a much higher risk than simply hiring a part-time receptionist. If sales fall and the need for that part-time receptionist goes away you really haven't lost anything. If the demand for Mike's services drops, he may be able to lay off that new hire, but he is still stuck with the payment on his new truck, or must sell it at a loss, therefore his risk for expansion is much greater.
There is also the fact that some companies are not driven by the near-term small increase in profitability alone, but rather they are looking at how these decisions can/may impact them 3-5 years down the road.
I worked for a small business some years ago that was VERY cautious about bringing in new people because they had a reputation they had built over a 15 year run of having never laid off an employee. They had an unusually generous benefit package, and really cared about their employees. Not every business owner is comfortable hiring 3 people short term unless they are fairly confident they can keep them on for quite a few years. They may bring on a few temps to help meet the demands of a short-term contract, but are we satisfied with calling that "job-growth".