Out here, hot water has more moving parts than it does in town. Plenty of properties run on propane instead of a gas main, some are on well water, and the far bathroom can be a long way from the unit.
Mineral heavy well water scales a heat exchanger faster than town water does. A propane unit has its own needs when it comes to supply and pressure. When a code shows up, either one can be behind it.
Someone comes out, looks at the unit and what it's connected to, and gives you the straight version, no runaround. If it's a repair, that's what you'll hear. If it's time for a new unit, it gets sized for your property.