No, I don't think you're missing anything. For many years, I installed the least expensive batteries in my vehicles and got ~5yrs out of'em.
Now with all of the electronics in vehicles today, I personally want the better/bigger/more powerful batteries in my vehicles with a longer reserve(e.g., if lights are left on).
W*M's low end/ECONOMY batteries may only be 12 months but, their EverStart & EverStartMAXX are 2 & 3 yr free replacement and then prorated from there, IIRC!
I also believe that batteries are made a little bit differently today. We're not getting as much for our money in the low end batteries as we once did. Maybe batteries are made better(overall) in terms of their power delivery & recovery in extreme conditions/situations. The higher end of battery you buy, the thicker the lead plates are(supposedly). However, to get the good STUFF means paying through the nose.
I mean, the batteries that I'd prefer to run in my vehicles(GOLD/PLATINUM etc.) are upwards toward $200 if your not careful. I see that W*M(MAXX) has what I want for ~$120 and AAP(PLATINUM) is ~$160. And you get some extra warranty...again which we probably won't use.