Nearly ev ery database application software is the same fundamental structure . . . front end (actual application/user utility), database and back end (reporting and modification tools). Quickboks, DiamondTouch, Point of Success, proprietary software for a hign volume law firm. Three pieces all working together to perform spec tasks and functions.
See, the key is in the design and development costs to make all those pieces perform the desired functions. Some software will perform the Pizzeria needed functions, and some will not. Same structure of software, possibly the same underlying database platform and backend tools. It all depends on how you configure them and the utility for given tasks.
Now, after I’ve paid these developers to create and program the application, connect the front, database and back together; paid development time with proprietary software and hardware engineers to make their piece work with mine; live tested the application in real pizzerias; developed patches and functionality to support myriad hardware configurations, including jacked up used junk from eBay; and so on . . . I am a business and need to recover the R&D costs plus profitability to operate my business. This is not unlike a pizzeria.
Some companies choose to bundle hardware together and sell their product as a turnkey system. Some put service contracts into the bundle and sell for more. It is all about the company model and how they intend to make their profitability goals. If I am making fewer sales, then I gotta get more money on the sales or find another revenue stream, like service contracts. If I can bundle hardware, then I can get some acceptable markup reselling the new hardware. Consumers take the chances and pay their nickels on the package of services, funtionality and harware they can afford or desire.
I doubt anyone in the business of making pizzas has the time, financial resources and expertise to develop even the simplest of Pizza POS applications. So, we pay someone else to do it for us.