Once the metal backing plate hits the rotor, the rotor goes to crap really fast. Doesn't take long to really mess it up.
The rear pads wearing fast has been a "thing" on every vehicle I have owned since 2007. That is when I first started noticing it. However, it also has been my experience the stock rear pads on all the new vehicles I have had were an organic pad that wears "quickly", replacing the pads with a ceramic or semi-metallic seems to have much better life and they wear at a more reasonable rate. Nothing wrong with organic pads but they do wear quicker than other mixes. There are Pos/Neg to each mix style.
I can't see being near the coast necessarily causing premature wear. I can see being near the coast causing rust issues. Maybe in my head, I can see if rotors are getting really rusty between drives that then the pads are doing some extra work to clean the surface off every time?
Either way, checking brake pads is a maintenance item. Every time I rotate my tires, which I do myself, I check the pads and watch for wear. If you have the tire store rotate, you can also ask them to give the brakes a check. Pretty much everyone recommends a 5000-7500 mile rotation, so that works pretty well for keeping track of pad wear.