Looking at the names of businesses that I have come in contact with over the years, it dawned on me that not all of them are traditional retail stores, bars, or restaurants. The ability to use smart phones or tablet computers as point of sale systems means that service related businesses (ie - lawn mowing, food delivery, waste pick-up) without physical stores can now have full fledged mobile point of sale systems that track the sale of products and services as well as authorizes payment.
Point of sale also expands into several government agencies. For example, a states transportation department or fish and game department needs to track the sales of permits and related fees. I've found that retail point of sale systems work great for this (and has been in use for several years with some of the departments that I have personally worked with).
Many government agencies also run golf courses with pro shops, ice rinks/rec centers, or restaurants which is also a great fit for a point of sale system. Finally, I've even worked with Sheriff's and EMS services as they use retail point of sale systems to track inventory.
Point being - the point of sale 'world' extends well beyond traditional retail stores, restaurants and bars.