Believe it or not, there are standards here in the US.
In the electrical power industry (read Power Company), the standard voltage for almost all single phase services is 120/240. The reason that you will most likely measure something slightly different at an outlet in your home is because of economic reasons. There must be an allowable tolerance in the voltage at which you are served. It is not impossible to keep things at 120 plus or minus 1 volt, but it would be very, very expensive to do so and of course as you know, it is not necessary either. Almost all equipment that you have in your home or business is designed to operate with a voltage that fluctuates plus or minus 5% from “center of band” or 120 Volts. That same plus or minus 5% holds true for services at other voltages as well. If you are a large industrial customer who requires 480 volt service for your large motors and equipment, that equipment is designed with that tolerance in mind. Right now in the USA, there are almost 500,000 people working hard to make sure that the voltage where your toaster is plugged in is as close to 120 as we can get it. (within those economic constraints of course)
People monitor those voltages 24/7/365 along with alot of other things.
We absolutely do NOT want you to wake up some morning and have to do without your toast, coffee, and whatever. ('Cause you’re pretty grouchy without that coffee…)
Electrical Safety is no accident. Learn Not to Burn.
Given the legend in the panel, the original range was electric using a 4 or 3 wire receptacle (depending on age of home). After the kitchen remodel, they opted for a gas range which now uses a standard 15 amp receptacle. Instead of pulling new conductors for the newly changed receptacle, they used the existing ones and pigtailed smaller conductors to terminate onto the 15 amp receptacle. Original 2-pole breaker was taken out and replaced with two single 15 amp breakers. One of those breakers is now being used for the new gas range.
Not a huge issue about the unused breaker in the ‘on’ position. Just recommend an update of the panel legend via sharpie.
110/220 vs 120/240. Tomato/Tomahto Potato/Vodka. Intermingled. Majority of appliances are made to operate on a 10% voltage stray and a 5% frequency stray.